[LAU] LV2/MIDI plugins missing in Ardour

Hi, there! My son brought to my attention, that my debian testing based media machine has some trouble finding some LV2 plugins with Ardour, although they are installed on the system. Must have been happen a few days ago with a simple use of "apt upgrade", 'cause he said that the last time he fiddled on some tracks everything was just in place. At least, there are three plugins he would like to use, which are not there anymore: drumkv1, samplv1 and odin2. drumkv1 and samplv1 are from debians repository, odin2 is from the homepage of "TheWaveWarden" (https://www.thewavewarden.com/odin2) - it has some packaging issues (the name of the package is the same as another package in debian's repository) but I can't imagine this has something to do with my problems. drumkv1 and samplv1 got upgraded, recently. But the Ardour package is the same since october… I already tried a new scan for plugins from inside Ardour, but all I got was some VST plugin additions which is nice but not what I intended to get. So, I'm a bit confused: There are some LV2 plugins from /usr/lib/LV2 that are usable from within Ardour and some are not. I just don't know, what to do, now… Greets! Mitsch