I know it has been a while, but just in case anyone is out there looking for the solution...
Facebook is forcing you to complete their "3-step process" (specifically step 2) before the "Go Live" button is enabled.
Essentially, after you start your stream from OBS, you simply need to go over to the "Add post details" area and fill out accordingly.
Select "What's your live video about?" and you will be able to enter in the required information (Title and Description).
After which, select Save, and that beautiful "Go Live" button lights up as expected.
Facebook is forcing you to complete their "3-step process" (specifically step 2) before the "Go Live" button is enabled.
Essentially, after you start your stream from OBS, you simply need to go over to the "Add post details" area and fill out accordingly.
Select "What's your live video about?" and you will be able to enter in the required information (Title and Description).
After which, select Save, and that beautiful "Go Live" button lights up as expected.