I know this wasn't easy for you, chillaircon.

I can see the importance of running your VAT Liability reports. I'd like to share what I know about the issue you've experienced right now.

Currently, we have an open investigation about this error when running the VAT report. Rest assured, our software engineers are doing their best to fix this as soon as possible.

For now, you'll want to follow the steps provided by my peers ReymondO above. Since there are times unusual behavior like this is caused by too much cache on the browser.

If you're still experiencing the same, I'd suggest reaching out to our Support Team. They have the tools to pull up your account and add you to the list of affected users. This way, you'll receive an email once there's progress about the issue. You can provide this investigation number for a faster process: INV-59577.

For your future reference, you can visit our Reports page to learn more about running your business reports in QuickBooks Online.

Keep me updated after performing the steps or reaching out to our support, I want to ensure this is resolve for you. Just reply to this post and I'll get back to you.