Indexed Allocation on Units

I am having difficulty getting an indexed allocation to work reading from the AU ledger, applying a factor and booking an entry to the AA ledger. All limitations I've seen regarding the AU ledger in allocations is regarding an AU to AU allocation.

I can get it working as a Balance allocation but need it as a Transaction allocation for other reasons. I did manage to get a Transaction version working but haven't been able to recreate that success since a data refresh that destroyed the working allocation.

The purpose is to read the hours charged to a wage account, multiply by a rate, and book the resulting amount as an insurance accrual.