Trigger Update in Self Related Rows

I have a table of Permits that can have a one-to-many relationship to itself. Example Permit 100 could be related to Permit 200 and Permit 300. This relationship is expressed via a virtual column of type list with a formula of REF_ROWS(“PermitTable”, “PermitID”) named [Enlargements].
I have created a workflow for Update of PermitTable that triggers only when ISNOTBLANK([Enlargements]). This workflow executes an action in the PermitTable that uses the “execute an action on a set of rows”. For each row in [Enlargements] it then triggers an action to “set the values of some columns in this row”. In this action I set column GPSLocation to [_THIS].
That is the portion that does not want to function, so my question is how do I pass in the column from the row that initiated the workflow to set the values in the related rows to the same?

@Markus_Malessa Check the type of the column GPSLocation

I guess thinking about the problem just a bit longer would have helped. In the action to set values in this row I had to do GPSLocation - [PermitID].[GPSLocation] since the column of PermitID references the same table on the one side.