https://imgur.com/214aKZy
I noticed some free courses, the enroll button is not loading, it is normal?
Eg. https://www.udemy.com/course/winning-your-internal-battles-to-get-funded-for-women/
Probably something related to your account. I see enrollment button in the example link you have provided. Check out in incognito if it will load.
I login to other account it can work and incognito mode is not working for me
No enroll button means you are already enrolled.
To view any Free course later, add learn in the URL as shown below
https://www.udemy.com/course/winning-your-internal-battles-to-get-funded-for-women/learn
This is Udemy new feature ?
perhaps yes, they are testing UI, noticed a few changes already.
Year is ending so their UI team need to show some work for Appraisals

It's a bug, sometimes refreshing the page helps
Udemy shouldn't have made a different UI for free courses in the first place, it has created a mess, and now they are making it worse
I noticed this too, yesterday
yes, I noticed same issue, but once I Refresh the webpage, 2 or 3 times, it appears enroll button.
This happens to me when I'm in incognito using Chrome Version 87.0.4280.88 (Official Build) (64-bit), then I take that URL and open it on a regular Chrome tab and the enroll button is immediately displayed.
Refreshing the page up to 5 or 8 times even, closing and opening it again in incognito most of the time does not work.
Out of say, 10 of these issues, only two worked after refreshing it two or three times.