Time is going… So, at first, this is for User Object.
If you will use get_field() you will get OBJECT, but if you will set update_field() you must put ID or ARRAY_OF_ID (for multiselect field). It isn’t clear for using and I didn’t see an ACF tutorial for it.
Will be great have a fine tutorial in Documentation “How to use update_field() for complex objects like User, Taxonomy, etc”. Because in wp-admin you just click mouse & select, but in code you must use correct format $value.
At second, the question about “update_field() with field_taxonomy” is open.
