Hope you are doing well and sorry for the trouble.
Would you mind sharing the steps you are doing for sending documents for signatures?
What is the version of the OS and the Adobe Acrobat DC you are using? To check the version go to Help > About Acrobat and make sure you have the recent version 22.1.20085 installed. Go to Help > Check for Updates and reboot the computer once.
I am on the most current version of Acrobat Pro DC version using continuous release 22.1.20085. I am on MacOS Catalina version 10.15.7. Had the same issue yesterday and restarted my computer and had the same issue again today.
The steps I took are pretty straightforward, using "Request E-Signatures", where I sign and then it automatically sends to client for signature afterward. I think "Request E-Signatures" used to be called something else. This is related to the recent Adobe Acrobat updates. Thanks!