I experienced a similar issue in Ableton Live. I installed Shimmer and (I think because of some problems with the activation) the VST3 was not visible. Multiple reinstalls didn’t help either. It was visible in Reaper though.

My fix was to quit live, delete Live’s plugin database and start it again (https://help.ableton.com/hc/en-us/articles/360000794970-Resetting-Live-s-Database).

I deleted all files, but I guess the plugin database would have been enough.

After that is rescanned all plugins and all versions of the Eventide plugins were there.