Mediabay does "forget" scan results

C6.5.4
create a track preset: TTTT.trackpreset and save to location X
open MB > choose location X and search for TTTT
result: no entries
rescan location: TTTT now shows in results. ok.
close MB
open MB again > choose a location X and search for TTTT
result: no entries
…and round it goes
seems MB does not retain its scan results. this is also true for other media types.

also:
VST instrument/or plugin > save a preset XYZ
open load preset dialog of that VST instrument/or plugin: the just saved preset XYZ does NOT show
it also does not show in the MB although the file XYZ is present in the folder location where it was saved.

???

Did you try rescan your folder manualy?

yes, manual rescan of folder.
but when i open the MD later again the results are not rembered