Preflight - missing fixup custom checks

[m2ramos]

Sorry, I'm new to creating fixups so I don't know all the terminology.

I created a custom fixup and whenever I add a form field criteria to a check, the new custom check disappears from the pulldown menu.  If I try to recreate the check again with the same name, it says it already exists and to choose a new name.  How do I delete the check I created?  Is it stored somewhere on the PC or registry?  For example, in the pictures below, if I edit "Remove Batch Stamp (Custom14)" and add the form field shown in the 2nd picture and click OK, then "Remove Batch Stamp (Custom14)" will disappear from the drop down list and I can't use that name ever again.

[try67]

What's the exact version number of the application (You can find it out by going to Help - About Adobe Acrobat)? What's your OS version?

[m2ramos]

Acrobat DC 2020.006.20034

Windows 10 v. 1909