Difficult to say, but probably the problem was you tried to install by hand. You ALWAYS have to install ROM files using the webconf, so the LV2 presets can be generated properly.
I recommend you check this folder:
/zynthian/zynthian-my-data/presets/lv2
to see if presets has been generated, perhaps partially, for the Osirus or Ostirus engines. If so, remove all preset folders for these engines. Then, try to upload the ROM file again and wait until the process is finished. It could take some time to generate the presets.
If it doesn’t work, you should consider the possibility that the ROM file you are using is not well supported or it’s damaged. In such a case, we couldn’t help you too much with this, sorry.
FYI, i’ve recently verified the ROM install procedure and i’m pretty sure it works OK.
Regards,