A similar issue occurs when changing the size of a loop. I just wrote a post trying to explain it: https://forums.pioneerdj.com/hc/en-us/community/posts/205004326-Loop-Problem-with-video
A somewhat similar issue also occurs when you have a loop running and you try to use the "loop move" feature. I wrote about that a long time ago and nobody replied: https://forums.pioneerdj.com/hc/en-us/community/posts/204435386-Loop-Move-Quantize-Issue