Suddenly I discovered that all my MicroSDs which were not compatible with Tracker OG are now usable. Solution was easy: if you have any PSP (100x, 200x, 300x) (I used my 3006 model), just format this MicroSD with PSP and then drop your files here from PC. PSP formats it to FAT32 32kb cluster size. You can do the same in Windows, but IT WONT WORK. I try to find why this solution is working and what is the cause of not-readable MicroSDs, but shared info I gathered to this moment.