This is not the kind of service we want you to have, HollyJ.

As much as I want to assist you with this, our QuickBooks Online support has better access. They can work with you remotely, and also report this error to our product engineers. The resolve transaction/resolve difference should work when trying to match the transactions. 

I recommend reaching out to them again.

Here's an article with a video tutorial for your reference: Categorize and match online bank transactions in QuickBooks Online. See more video tutorials about QuickBooks here.

If there's anything else that I can help you with, let me know in the comments.