Very short loop on tape- will not let me record

I have an issue with the tape- it makes some kind of very short loop that just repeats itself.

i tried rebooting, i cleaned the tapes, and it’s all the same. it happens on all tapes (1-4).

Possibly too obvious a suggestion, but have you tried pressing the ‘3’ key (from the 1-8 keys, not the 1-4 tape track keys). That engages/disengages the loop, 1 sets the start point, and 2 sets the end point.