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The problem may require some trouble to find. Have you tried a different USB stick? it might just be the particular USB stick is having problems.
Have you tried a reset of your drum set? it might perhaps be having an internal processing error and need a reset to straighten it out. (Warning: a reset might erase settings stored on the drum set.)
Is there any symptom of an error?
How old is the drum set in question, quite new? how new, please? Has playing from the USB stick ever worked properly?
Are the playing sequences from the USB stick, recorded on this drum set, or recorded elsewhere / on another machine?
So the USB stick contains 'recordings' or sequences from another device.
Can you record onto the USB stick(s)? if so, try recording a test sequence, of >30 seconds length. Then try playing it back.. does it go through, or does it stop?