Why is turning on Ok Google detection buggy?

[Android Central Question]

I cannot turn on Ok Google detection. Google assistant is on, when I click the detection button it open something like a first page of an introduction, I click next and it sends me back to settings. I had an issue where the recent apps bugged a year ago and the fix was to turn some setting off. It was related to the whole Ok Google option. I can't remember what it was, I don't know if it is related. I want to ask my phone things even when it's on the table, anyone have an idea about this? I'm with Android 8 btw.