Thanks for trying that out. Unfortunately, the attachments aren't showing on this thread, so it might be worth you adding those again, however as this has resolved the issue for one bill it's likely that there may be a cache issue with the browser you're using which is causing this behaviour.
To test this, please try clearing the cache on the browser you're using for a period of all time, and then close/re-open the browser and re-create the bill as above. If you're unsure how to clear the cache, we've got a guide here which covers doing this on the supported browsers for QuickBooks Online. You can also try entering the bill on a different browser to identify if the issue is browser-related. 👩💻