Blue stains C-41

Hi Everyone!

I hope maybe one of you knows the solution.
I encounter continuous problems with blue stains on the negatives.

They are only visible after scanning. I did numerous tests, re-bleached, and re-fixed, checked the scanner, made fresh solutions with distilled water, pre-wet and not pre-wet, changed from Jobo Cpe2 agitation to the manual inversion agitation. I follow the instructions of the Fuji Hunt X press kit. The temperature is correct. Each time the negatives came out fine besides those randomly placed blue stains. I don't think it's my camera's fault as the stains appear in different places on some (not all) pictures of the negative.
Generally, it looks like a blue fog/leak/smudge, sometimes a spill, on one neg there is a continuous line, on another, there are even blue dots.

Please, could you advise me on what can be at fault?