This is not a big problem but I thought I wold mention it in case it saves someone else a few minutes:
In a process assigned to a table, if you call another process and want to select or populate a row, the LOOKUP() function requires you to specify [_THISROW] to refer to records in the table the calling process is assigned to.
So if a process is assigned to the table orders and I want to call a process and specify a row in the tables customers, the formula to find the record id would need to be something like
id = LOOKUP( [_THISROW].[email], “customers”, “email”, “id”)
This is different from a virtual column in the table orders where the formula would find the customer record without [_THISROW]
Not a big deal if you are aware of it.