I have a website in development in English with Welsh as the second language, and a strange behaviour has started which I cannot trace the source of.
I have a custom post type called profiles which work in the same way as regular posts and pages, and I have an ACF field group that is set to only work with this custom post type. These ACF fields are set to be translatable and when I create a new profile they show up as translatable fields as you would expect, however they are pre-filled with random text and there also seem to be other fields that don't correspond to fields I have setup (simply called field-0, field-1 etc. See screenshot).
I'm not sure when this behaviour started but I can say it was working fine to begin with so something has interfered somewhere. Older profiles that are already published don't seem to affected.