Hi there, @PegH.
I'm here to help make sure that you can void or delete your check by verifying and rebuilding your data.
Since you're getting an error, I recommend running the Verify and Rebuild Utility tool.
To run Verify Data utility:
Here’s how to run the Rebuild utility:
For additional troubleshooting steps, please refer to this article: Resolve Data Damage on your Company File.
After verifying and rebuilding the data, you can void or delete your check again to double check.
Please keep me posted on how things go with this. I'm here anytime you need further help managing your QuickBooks.