The great news is, you've come to the right place, and I have troubleshooting steps to help resolve this issue. To isolate this case, we can perform basic browser troubleshooting by clearing the cache to fix the issue.
There are times that the browser is full of frequently accessed page resources, causing some unusual responses. We can start by accessing your account in a private browser. This mode doesn't save your searches, visited pages, log in details, and cookies.
You can use the shortcut keys that I've listed below.
Ctrl + Shift + P (Firefox)
Command + Shift + N (Safari)
Ctrl+ Shift + N (Google Chrome)
Once you're in the Private / Incognito Window, sign in to your QuickBooks account, and verified amounts of credits and amounts of invoices were the same. Also, try selecting only one invoice and one credit to double-check If it works. Once works, then you can go back to your original browser and clear the cache. Alternatively, you can use other compatible browsers. It could be that the one you're currently working on has a temporary issue with QuickBooks.
Thanks for your reply. I was able to clear cache and sign in incognito. I was able to click on one bill and one credit that matched and it allowed me to save the zero payment. The other 1 credit and 7 bills that matched to zero I am still getting an error. Funny thing is that I also needed to do the same for a different vendor and it worked just fine I went to the other vendor and got the error.
Thank you for getting back to us here on the Community page, @CK18.
Since this only happens to one of your vendors, we can narrow down the cause of this error by deleting and creating the bills as well as the credits recorded. To delete each of them, select the Delete tab from the More button. This way, we can assure that the transactions are recorded correctly.
Also, I encourage checking the topics from these articles as your guide when managing vendor credits in QuickBooks Online: