Adding channel inserts do not always load

I have problems with adding channel inserts (audio channels and fx channels) where sometimes (appears random) a selected insert will silently refuse to be loaded as a track insert, no matter how many times it is selected.
And also for random project.

After closing, exiting and restarting Cubase I can sometimes get the insert to load, however then it will refuse to add the insert to another channel. Affected inserts include Izotope, Soundtoys, Clariphonic (KUSH AUDIO) and even Yamaha Compressor 276 (Steinbergs own) did not load in one project but was ok to load in another. This goes for both VST2 and VST3.

All updates have of cource issues but I do not want to go back to Cubase 9, though this release is wasting much of my time.

I am running WIN-10 pro with the latest update, i7 cpu, 12 GB ram