I have this exact issue with the latest linux editor, but it was supposedly fixed in 2017.3:
Can anyone confirm or deny they experience the same issue in the latest linux editor? Other snapping like vertices using (V) seems to work fine - just the grid that doesn’t.
I’ve tried the snapping in 2017.2.0f3 and it works fine, so this does seem to be a 3.0f1 bug, for me at least. If so, how anyone is using this version escapes me!