Hi @munnerlyna,
Thank you for the detailed triage, and we understand how disruptive this is when you have licenses available and are ready to assign them.
Since you've already tested a different browser, a fresh sign-in, and a second admin account, you've covered the factors on your end that typically cause this. When the Error ID comes through blank, it points to the save failing on the service side rather than an issue with your console setup. As a first step, we'd recommend waiting a short while and then attempting the assignment once more.
If the same error continues, please open a case through Admin Console > Support and include a screenshot of the error. Our support team can access your account directly and resolve this from the backend.
Please try the assignment again after a brief wait and let us know how it goes.
Thanks,
^AV