You’re surely right foxviewr, I already tested regressing to previous WPML version and reported the issue to WPML suppor forum (where I found huge amount of people in similar situation).
I just felt that was good to report this issue here too, for some reason even with the buggy last version of WPML, if I use ACF 4.4.0 with repeater and flexible content addons, instead of ACF Pro, everything looks fine.