Also posted this on the Bb ListServ but thought I would share here too:
We have discovered that all admin users are not able to quick enroll in courses when Google Chrome is automatically updated to version 76. If we roll back to version 75, we can quick enroll.
It will let you quick enroll and acts like it happened but never actually enrolls you in the course as an instructor.
I have submitted a case to BB Support and you can reference the it if you have the same issue: Case #04224679
We are on 3400.0.4-rel.68+a1c490e or Learn 9.1 2018 Q2 CU4 and self-hosted right now.