I'm currently on 5.0.2+
I've got the Stripe plugin and have enabled 'Enrol on payment' as an enrolment provider.
During testing, I've set the course cost to zero. I still hit the enrolment screen, and am told that there's no cost to enrol .. .but there's also no button to enrol either.

I checked the code inside the enrol_fee plugin and sure enough, when it's showing the 'no cost' message, it's not even creating a button.

Is this by design - i.e. it is intentional that there shouldn't be a way to enrol if there's no price set - or is it an oversight/bug? If there's no price, and I'm told there's no cost to enrol, but then given no way to enrol, that seems like a bug.