Where is the "solved" checkbox?

Possibly suffering the effects of old age, but I can't seem to find the button to flag a post as the solution to my issue. Has it gone away, or am I just looking past it?

Some categories have it. And some don’t. Where is it missing ?

In Core Development/Feature Requests. I wanted to mark this post [Solved] Restarting flows programmatically - #2 by TotallyInformation.