The alt+click shortcut to enter a value into a modulation assignment immediately after assigning it causes a visual error where the initial value is stuck but can still be changed elsewhere, and you are unable to enter a value.
I’ve noticed more often than not that you have to click away elsewhere on the interface to make that modulation circle disappear and then re-hover over it for the error to not occur, and if it does occur then you have to close and re-open the plugin to be able to alt-click and enter a value.
I am using the latest edition of Vital at the time of this post (1.0.7) in Ableton 11 on Windows 10, though this is something I noticed since launch on Ableton 10 as well.
Btw I LOVE this synth and the unique sound design capability it has, this bug makes it a lot less speedy though :[