Allow me to help and get this working for you, Nicky Morrison.
Your browser’s overloaded cache could be the reason why you’re unable to save recurring sales receipts. It tends to hold information that can cause issues once overloaded.
To isolate the issue, try entering the sales receipts on a private browser or incognito. Being able to do this successfully indicates the said issue above.
If you're able to save the recurring sales receipt, go back to the regular browser. Then, clear the browsing history.
Follow the steps to clear the history for your browser.
Once done, make sure to restart your browser for changes to take effect. To have the best and most secure experience with QuickBooks Online, use a supported, up-to-date browser.
After performing those steps above, you can enter again the recurring sales receipts.
If you're still unable to save the transaction, I recommend contacting our QuickBooks Live Team. That way, they can create a case and forward it to our Product Team for further investigation.
If you have a timeout issue, make sure to set the duration to 3 hours for all users. Check out this link to learn how to do it: Change the timeout duration in QuickBooks Online.
Keep me posted if you have follow-up questions by commenting below. I'll be around until you're able to save recurring sales receipts.
