I’ve run into keyboard issues like this long ago with VCV 0.6 and 1.0. My Seq++ wants to use keys that rack is already using. In stand alone rack it it possible to grab them anyway, BUT…
I found that it was a bad idea on my part to try and “steal” keys that are commonly already used. The user experience is kind of bad. My “solution” was to make all the keys in Seq++ re-mappable (a good feature anyway).
If I were doing it again today, I would for sure not use a commonly used key (like ctrl-z, for example) in a default keymapping. Especially if the VCV plugin doesn’t allow you to re-map.