I did some more digging and it seems that if “MY_OPTIONS” evaluates to a valid taxonomy name that your fields might be save incorrectly.
When ACF tries to figure out where it should be saving a blue it explodes the post ID resulting in
array(
'MY',
'OPTION',
'PAGE'
)
then it combines all but the last value of the array and looks to see if that is a valid taxonomy.
Anyway, I’d do a search of my database to see exactly where the values are being saved, if they are being saved at all.
