This is bizarre... so.. after further testing here's what I'm finding...
If I click "Enrol cohort" BEFORE the enrolled users page is finished loading, I end up with the Cohort Sync option. If I wait until the page has COMPLETELY loaded and click the "Enrol cohort" I get the pop-up window as expected.
I have been able to replicate this behaviour in at least 15 of our courses on our site. I can't imagine that this is real - it's just too bizarre. I'd appreciate if someone could do further testing to confirm. If this does get confirmed - would it be considered a bug? If it's not, then perhaps something in the pages for Cohort enrollments would be appropriate.
Thanks,
Leah