Create a filterable array of record IDs

I have record IDs being looked up across several tables. So table B looks up the ID formula (row_id()) from table A, and table C looks up the linked IDs from table B, but for some reason I cannot create a string with join() in order to make the field searchable in the API. However, it works with other fields.

@bgschust Can you provide the exact formula you are using? I’m able to join together a lookup of row_id() formulas using join(totext(field('row id formula')), ',')

Thank you! I was missing totext().