From Stock Invoice (no SOP), to be able to view warehouse Merged

I had a customer who had an issue posting an invoice and it said there was insufficient stock, even though there was plenty in the warehouse he said he selected. After much investigation, i had to look into the Warehouse item table to discover the wrong warehouse was selected on a number of lines. The warehouse selected isn't viewable after selection or after saving the invoice. This makes it very difficult to find out what went wrong so stock could be transferred to the warehouse selected to work around and is very hard to prove until you delve into the data. Can there be a way to see what location was selected please?