PPS: even more weird - after seeing the set of maps and POIs work, I did some other stuff with tracks (incl. screenshots), then stopped over night, but left LM4 active (as a service). Trying POIs after breakfast, it did no longer work!
Removing some maps did not help, removing some more neither, always with cache removal by Locus.
Only de-install and re-install of LM4 helped, i.e. it now works again, but for how long ?
Can there be any mechanics that would turn a working setup into a non-working one - just by elapsed time ?
Or by doing any stuff that changes and takes memory (like my track actions, and screenshots) ?