I’m getting the same “Illegal offset type” error, whether I try this with a single select item or multiple selected. I’ve tried every which online suggested way, removed all other plugins other than CPT UI (required), and with the latest (5.8.7) ACF Pro and standard editions. The error is thrown whether the return format is “Both (Array)” or not.
If for instance I follow the instructions to Display value and label at https://www.advancedcustomfields.com/resources/select/https://www.advancedcustomfields.com/resources/select/, the offset error is on the line containing [‘choices’].
And if I follow the Format value setting instructions, with the return format set to “Both (Array)”, the error is again thrown on the line containing [‘choices’]. If I change the word to something meaningless – [‘blah’] – there’s no illegal offset error, but of course no output there either.
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users
Helping others is a great way to earn karma, gain badges and help ACF development!