This may be a tiny bug but it shows up in the Content Validator, hence this post.
If you remove a field from your LookML and there’s a field missing in a Look/Tile, you can go there and “do something” to save the content again. You can’t really delete it from the query because it’s already gone.
The problem is that sometimes the Content Validator will still report a missing field because it’s still in the ‘”sorts” parameter. I found it by downloading LookML of the dashboard.
In my case it was a second sort, so I had to go back to the tile and sort it again by the primary one, only then the underlaying LookML was changed correctly