Without getting into the deep weeds, I have some initial questions.  

1. Are you familiar with FIFO (First In First Out) inventory accounting?  QBO uses this.

2. Are you receiving inventory using a PO? (even if you didn't do this for the Supplier, do it when attempting to process the correction, this preserves FIFO practices)

3. Are there any period limits being enforced for the time frame you are allowed to enter transaction?

If none of these conditions apply, you should be able to create a proforma PO which fully documents the fix, receive the goods on the original date and the transaction would appear in proper sequence to modify your QOH.  Please be sure that you have not modified the SKU between the time you first ordered and the present.  Something that simple can generate an error message.

Also, check for inventory adjustment transactions for that SKU.  These do not follow FIFO rules, by definition.  You may need to remove the adjustments (if any).

Kevin