On Dashboard, Monetize, Project Settings.
There is Ads Provider. It was not defined. I put Unity.
I decided to see what would happen if I tried other options.
I tried Self Mediated. OK, curiosity satisfied, nothing particular. I wanted to go back to Unity. It had disappeared from the list.
I tried Other then, to see if perhaps the Unity option would return. Nope.
I tried AdMobs then but it failed. I reloaded the page and it displayed Unity. I reloaded that page again and it went back to Other.
How do I put it back to Unity and could we have more information and some direct link to explain what goes on there too? Thanks.
PS: There is no link, no (?) in the dashboard to provide a modicum of information of what each element does.
Hey @Starbox thanks for reporting this. I will pass this feedback to the dashboard team.
I also got this issue now; my game has been delinked from the project and I can’t relink again. Could both be related? It’s weird, I never had that before.
I tested the vertical three dots button, top right of an ad placement’s page. There was a surprise option (hehehe) there to let me use Platform specific settings.
I had decided previously to use separate iOS and Android ad placements so I thought it might be good for me to provide even more info on how each placement is meant to be used.
So I went inside all those ad placements I had created which were meant to be specific to either iOS or Android, and opted to have that “platform specific setting” option, then set it up adequately every time.
In the small menu, iOS is the first option and Android the second.
Every time I return into the setting of the Android placements, the option has reverted to iOS.
That’s obviously a bug.
So between the Unity option that disappears as described earlier on and the platform setting that stays stuck on iOS, you’ve got two bugs going on.
I also didn’t see any button to opt out of platform specific settings either, which would have been nice. 
Hi!
It would be cool to have at least some info on what this option is and does. I leave it undefined for now but if it helps increase income, I’d be happy to set it.