Paid event registration error: "There was an error while performing the operation. The page will be refreshed."

We have recently upgraded to SP38 in our test environment, and are currently testing. We're encountering a known issue described in this article in the knowledge base: https://kb.blackbaud.com/knowledgebase/articles/Article/205920. Basically, when trying to complete registration in a paid event in BBIS, on the payment step we get: "There was an error while performing the operation. The page will be refreshed." We then have to refresh the page and then can finally complete the process.

We tried implementing the workaround suggested in that knowledge article linked above: "enabling the Additional Donation feature on the affected Event Registration Form part showing this error should allow the transaction to process successfully on the first attempt. " This does allow us to complete the transaction on the first try, however now it gives us a popup for an additional donation that we don't want and we can't seem to get around.

I'm wondering how other folks who encountered this refresh issue dealt with it - especially if you don't want to prompt for additional donations.

Thanks!