REGEX_MATCH formula works on one table and not the other

Hello,

I’m pulling my hair out… I have the following formula:

REGEX_MATCH({Products},"Personal")
{Products} is a ‘A Name’ column and the above formula produces a 0 if “Personal” is not present in the column’s field and a 1 if “Personal” is present in the column’s field.

Using the same formula on a different table:
REGEX_MATCH({Products},"Personal")
{Products} is a ‘Lookup’ column and the above formula produces a 0 if field is blank and a #ERROR! if not blank.

The only difference between the two scenarios is the top formula is checking a ‘A Name’ column and the bottom formula is checking a ‘Lookup’ column.

What am I missing? Why am I getting an #ERROR!?