Adding Simple VCF works in my debug version of Rack v2.2.1 (built from source) on Win 10, but trying to delete the module from the rack crashes:
warning: HEAP[Rack.exe]:
warning: Heap block at 000001C6ECE46FE0 modified at 000001C6ECE46FF8 past requested size of 8
Thread 1 received signal SIGTRAP, Trace/breakpoint trap.
0x00007ffee7a4a773 in ntdll!RtlRegisterSecureMemoryCacheCallback () from /c/WINDOWS/SYSTEM32/ntdll.dll
(gdb) bt
#0 0x00007ffee7a4a773 in ntdll!RtlRegisterSecureMemoryCacheCallback () from /c/WINDOWS/SYSTEM32/ntdll.dll
#1 0x00007ffee7a46dff in ntdll!RtlZeroHeap () from /c/WINDOWS/SYSTEM32/ntdll.dll
#2 0x00007ffee7a0cf5a in ntdll!memset () from /c/WINDOWS/SYSTEM32/ntdll.dll
#3 0x00007ffee7a49621 in ntdll!RtlRegisterSecureMemoryCacheCallback () from /c/WINDOWS/SYSTEM32/ntdll.dll
#4 0x00007ffee7975cc1 in ntdll!RtlGetCurrentServiceSessionId () from /c/WINDOWS/SYSTEM32/ntdll.dll
#5 0x00007ffee7975b74 in ntdll!RtlGetCurrentServiceSessionId () from /c/WINDOWS/SYSTEM32/ntdll.dll
#6 0x00007ffee79747b1 in ntdll!RtlFreeHeap () from /c/WINDOWS/SYSTEM32/ntdll.dll
#7 0x00007ffee6b69c9c in msvcrt!free () from /c/WINDOWS/System32/msvcrt.dll
#8 0x00007ffea583c5ba in plugin!_ZN12SimpleFilterD0Ev () from /c/Program Files/VCV/Rack2 Pro/plugins/LindenbergResearch/plugin.dll
#9 0x00007ffeac747eb5 in rack::app::ModuleWidget::setModule (module=0x0, this=0x1c6fa189fb0) at src/app/ModuleWidget.cpp:70
#10 rack::app::ModuleWidget::~ModuleWidget (this=0x1c6fa189fb0, __in_chrg=<optimized out>) at src/app/ModuleWidget.cpp:50
#11 0x00007ffea5844981 in plugin!_ZN18SimpleFilterWidgetD0Ev () from /c/Program Files/VCV/Rack2 Pro/plugins/LindenbergResearch/plugin.dll
#12 0x00007ffeac74e025 in rack::app::ModuleWidget::removeAction (this=this@entry=0x1c6fa189fb0) at src/app/ModuleWidget.cpp:933
#13 0x00007ffeac74f052 in rack::app::ModuleWidget::onHoverKey (this=0x1c6fa189fb0, e=...) at src/app/ModuleWidget.cpp:353
#14 0x00007ffea57b4397 in plugin!_ZN3lrt14LRModuleWidget10onHoverKeyERKN4rack6widget6Widget13HoverKeyEventE ()
from /c/Program Files/VCV/Rack2 Pro/plugins/LindenbergResearch/plugin.dll
#15 0x00007ffeacc021ab in rack::widget::Widget::recursePositionEvent<void (rack::widget::Widget::*)(rack::widget::Widget::HoverKeyEvent const&), rack::widget::Widget::HoverKeyEvent> (e=..., f=&virtual table offset 112, this=0x1c6ecc81b00) at include/widget/Widget.hpp:197
#16 rack::widget::Widget::onHoverKey (this=0x1c6ecc81b00, e=...) at include/widget/Widget.hpp:284
#17 0x00007ffeac75afc7 in rack::widget::Widget::recursePositionEvent<void (rack::widget::Widget::*)(rack::widget::Widget::HoverKeyEvent const&), rack::widget::Widget::HoverKeyEvent> (e=..., f=&virtual table offset 112, this=0x1c6ec791630) at include/widget/Widget.hpp:197
#18 rack::widget::Widget::onHoverKey (e=..., this=0x1c6ec791630) at include/widget/Widget.hpp:284
#19 rack::widget::OpaqueWidget::onHoverKey (e=..., this=0x1c6ec791630) at include/widget/OpaqueWidget.hpp:30
#20 rack::app::RackWidget::onHoverKey (this=0x1c6ec791630, e=...) at src/app/RackWidget.cpp:176
#21 0x00007ffeacc00915 in rack::widget::Widget::recursePositionEvent<void (rack::widget::Widget::*)(rack::widget::Widget::HoverKeyEvent const&), rack::widget::Widget::HoverKeyEvent> (e=..., f=&virtual table offset 112, this=0x1c6ecbe0950) at include/widget/Widget.hpp:197
#22 rack::widget::Widget::onHoverKey (e=..., this=0x1c6ecbe0950) at include/widget/Widget.hpp:284
#23 rack::widget::ZoomWidget::onHoverKey (this=0x1c6ecbe0950, e=...) at include/widget/ZoomWidget.hpp:35
#24 0x00007ffeacc021ab in rack::widget::Widget::recursePositionEvent<void (rack::widget::Widget::*)(rack::widget::Widget::HoverKeyEvent const&), rack::widget::Widget::HoverKeyEvent> (e=..., f=&virtual table offset 112, this=0x1c6ecca5050) at include/widget/Widget.hpp:197
#25 rack::widget::Widget::onHoverKey (this=0x1c6ecca5050, e=...) at include/widget/Widget.hpp:284
#26 0x00007ffeac77c49c in rack::widget::Widget::recursePositionEvent<void (rack::widget::Widget::*)(rack::widget::Widget::HoverKeyEvent const&), rack::widget::Widget::HoverKeyEvent> (e=..., f=&virtual table offset 112, this=0x1c6eca97d80) at include/widget/Widget.hpp:197
#27 rack::widget::Widget::onHoverKey (e=..., this=0x1c6eca97d80) at include/widget/Widget.hpp:284
#28 rack::widget::OpaqueWidget::onHoverKey (e=..., this=0x1c6eca97d80) at include/widget/OpaqueWidget.hpp:30
#29 rack::ui::ScrollWidget::onHoverKey (this=0x1c6eca97d80, e=...) at src/ui/ScrollWidget.cpp:175
#30 0x00007ffeac76436d in rack::widget::Widget::recursePositionEvent<void (rack::widget::Widget::*)(rack::widget::Widget::HoverKeyEvent const&), rack::widget::Widget::--Type <RET> for more, q to quit, c to continue without paging--c
HoverKeyEvent> (e=..., f=&virtual table offset 112, this=0x1c6ecafbae0) at include/widget/Widget.hpp:197
#31 rack::widget::Widget::onHoverKey (e=..., this=0x1c6ecafbae0) at include/widget/Widget.hpp:284
#32 rack::widget::OpaqueWidget::onHoverKey (e=..., this=0x1c6ecafbae0) at include/widget/OpaqueWidget.hpp:30
#33 rack::app::Scene::onHoverKey (this=0x1c6ecafbae0, e=...) at src/app/Scene.cpp:323
#34 0x00007ffeac784a99 in rack::widget::EventState::handleKey (this=this@entry=0x1c6eca8c360, pos=..., key=key@entry=261, scancode=scancode@entry=339, action=action@entry=1, mods=mods@entry=32) at src/widget/event.cpp:334
#35 0x00007ffeac7867e9 in rack::window::keyCallback (win=<optimized out>, key=261, scancode=339, action=1, mods=<optimized out>) at src/window/Window.cpp:224
#36 0x00007ffeac7ce4b5 in windowProc (hWnd=0x903b8 <plugin!_ZN3stk5Delay5addToEdm+14264>, uMsg=256, wParam=46, lParam=22216705) at C:/_Projects/VCVRack/V2/Rack_SR/dep/glfw/src/win32_window.c:769
#37 0x00007ffee65be858 in USER32!CallWindowProcW () from /c/WINDOWS/System32/USER32.dll
#38 0x00007ffee65be4ee in USER32!CallWindowProcW () from /c/WINDOWS/System32/USER32.dll
#39 0x00007ffed6b2f0f0 in glPushClientAttrib () from /c/WINDOWS/SYSTEM32/OPENGL32.dll
#40 0x00007ffee65be858 in USER32!CallWindowProcW () from /c/WINDOWS/System32/USER32.dll
#41 0x00007ffee65be299 in USER32!DispatchMessageW () from /c/WINDOWS/System32/USER32.dll
#42 0x00007ffeac7d0a53 in _glfwPollEventsWin32 () at C:/_Projects/VCVRack/V2/Rack_SR/dep/glfw/src/win32_window.c:1981
#43 0x00007ffeac786cc9 in rack::window::Window::step (this=this@entry=0x1c6ec912a90) at src/window/Window.cpp:430
#44 0x00007ffeac787648 in rack::window::Window::run (this=0x1c6ec912a90) at src/window/Window.cpp:408
#45 0x00007ff70e9d169b in main (argc=<optimized out>, argv=<optimized out>) at adapters/standalone.cpp:244