I got on the phone with a human. A very nice gentleman. We tried different things to no avail. I tried to make a new invoice and it saved! My solution for exist...
What you describe is same for me. Problem happened after new QBO updates. Existing invoice, can’t save and keep qty changes. Just a simple red error message say...
I have a product/service entered in on every line item on a past invoice already saved. I need to send final invoice now the job is complete, all I did was edit...