With the 64 Bit version of Reader (21.011.20039) you're unable to open XFA based forms. All you get is an error message saying "no error". After clicking [OK] you only see the Shell-PDF with the "Please wait …" hint. The XFA content isn't processed. The 32 Bit version seems to be fine but automatically gets updated to 64 Bit after some time.

It's the same bug as last year.
https://community.adobe.com/t5/acrobat-reader-discussions/error-message-quot-no-error-quot-when-trying-to-assemble-an-xfa-based-pdf-in-latest-version-of/td-p/11835486