However, one of them lacks the ORDER_FACT table, and that is because I mischievously removed it by clicking Modify and then unchecking it from the source tables list.
This ID’s mapping is still automatic, in that that it will use any new table that contains CUSTOMER_ID and it will remove from its definition any table that cease to contain this column. But as far as the table ORDER_FACT is concerned, it will not be used by the attribute until it is checked again in the source table list.

So, when debugging reports which don’t run because a fact appears not to be available at a certain attribute level, do yourself a favor and check if that particular attribute suffers from what I have described above.