Hi,
I’m trying to create setup based on VCV and Lemur. Lemur https://liine.net/en/products/lemur/ is another “create your own controller on a tablet” app similar to TouchOSC etc. so if anyone has experience with these apps, please also let me know!
Most irritating bug so far is related to @marc_boule’s MindMeld mixer. In Lemur I have 2x16 rows of switches to control SOLO and MUTE buttons via @stoermelder’s MIDI-CAT and always have a visual feedback in Lemur about current status. Sometimes I press a switch and nothing changes. I understand (perhaps wrongly) that there’s some well known bug with midi messages being sent only once per audio buffer. My buffer now is at 128 and still some messages get skipped. That would annoying but be ok-ish, but the real problem is that sometimes the MUTE/SOLO switch not only skips one message but starts ignoring all following attempts to switch it. The switch get stuck, until I use computer mouse to switch it directly in Rack. Then everything continues to work normally. Surprisingly I really didn’t notice same behaviour with other modules I try to control with switches.
Right now I mostly want to pinpoint the reason of the problem. Is it MIDI-CAT, MindMeld, Lemur, VCV handling of midi messages, my midi routing settings? After a week of suffering I’m kinda lost and not even sure how to start debugging properly 
Any advice or sharing of your own experience with MIndMeld+controllers would be highly appreciated!
@stoermelder I also have one question related to MIDI-CAT. Once again, I thought that midi messages are received by Rack once per buffer (I think I read it somewhere? Perhaps misunderstood). What exactly does “precision” option do then. Does it somehow override messages frequency?
MIDI messages are processed once per audio buffer by Rack. In most cases this is not a big issue but it causes jitter especially when using a MIDI clock. It does not cause skipping messages! I would hardly call it a bug, it is some limitation of the MIDI implementation in Rack v1. In Rack v2 timestamps for MIDI messages will be available.
The „precision“ setting is new in the upcoming version 1.8.0 and the module‘s manual has not been updated yet. It sets how offen the mapped parameter is updated by MIDI-CAT and is especially useful when slew-limiting is used for a mapping-slot. Slew-limiting can cause quite high CPU usage if done at audio rate which is not necessary most of the time.
This been said I want to add that you are using a version of MIDI-CAT which is not fully tested yet.
Oh, so i did get it wrong, and everytime I get the message skipped - it is a sign of bug, not some Rack MIDI limitation. That’s an important info for me, thanks a lot!
Yeah, I’m aware that I’m using dev version, I use it since you fixed a minor but important for my current project bug 
However I think now that my problem is not related to MIDI-CAT, since when the message is skipped, MIDI-CC module also doesn’t show parameter change… Looks more and more like Lemur stability problem.
Pretty sure its not the MM mixer - I use a Midi Fighter Twister to control mute/solo and never had a problem.