MMEX Instance Check - Unable to Access an Account

[Wirmike]

I have started to get “MMEX Instance Check” messages again.
I think that this may be a result of an error in my part, I hope you can help to resolve.
The report only occurs after trying to access a particular account in my database. All other accounts (bank, shares, assets) appear to work okay.

I have been making a good deal of use of the Tag feature - it has proved to be very helpful.
I tried adding new Tags to each of three Split Categories on the same transaction. Each Tag was different. After I added the first, all seemed well, but after adding the second and third I discovered I was unable to access the account that the transaction was in (actually a Credit Card [CC] account,) Clicking from the Navigation Pane on the account only resulted in the spinning colour wheel. I quit MMEX and re-launched. I was then presented w/- the “MMEX Instance Check”.
I clicked to continue. MMEX then loaded, seemingly fine. All accounts appeared to be able to be accessed okay, EXCEPT the CC account in question, selecting again returning the spinning colour wheel.
Are there any issues with the limitation of characters in the name of a Tag?
In an attempt to remove a potential problem, I renamed all three of the Tags that I had created to be alpha-numeric, w/o the % sign. I still used the apostrophe as a spacer between words, as I have w/- the many others I have already created - thinking that renaming could be a sort of back-door to a cure. But it made no difference. I still cannot access the account in question!
Can you help?

MMEX: 1.8.1;
MacOS: 14.6.1;