Reaper *not responding* after selecting envelopes for a track

[Elle]

Hello, every time I try to put an envelope on my track, Reaper stops responding entirely until I have to force close it. More specifically, it crashes every time I try to pick a specific envelope for a VSTi I'm using.

The plugin I'm using is Kontakt 5 - Una Corda, and I'm trying to automate the "Reverse" envelopes.

Any suggestions would be helpful, thanks!