Cannot install mono to install Sonarr

I’ve had similar issues - the dependency errors. Followed the instructions to alter the pin priority, then removed the file afterwards (there was nothing else in it) to set the pin priority back to normal.
This is all fine, and Sonarr works, successfully downloads, and remains after reboot.
Until OSMC does its updates.
Whenever OSMC checks for updates, it says there’s some available and needs to reboot. Once it’s finished the updates, Sonarr has disappeared.
By default, Sonarr is installed into /opt/NzbDrone and once OSMC does the updates, NzbDrone is completely removed from that folder and I have to start the install again. My library remains, so I don’t need to re-add stuff, but the install directory is gone.

Any thoughts on what’s going on here, and how I can stop it?
For now I’ve put all the install steps into a script, that I manually run after OSMC removes it…