Sometimes I don't gain or lose rating after doing a puzzle

[nallcho14]

Spent a decent amount of time to solve today's daily puzzle(#G4ijX) but didn't gain any rating. I also sometimes don't lose rating when I fail a puzzle as well. I never play unrated puzzles so it wasn't that.

[nallcho14]

just looked at my puzzle history and it said that I did this puzzle 10 hours ago. Says I failed a puzzle today and dropped to 2189 didn't remember doing that. Think my brother failed the puzzle on my account earlier I'll ask when he wakes up.
But still it's not the first time I didn't gain or lose rating after doing a puzzle, also happened when doing a non-daily puzzle some time ago

[AnAlgorithm]

This might be because you have already solved the puzzle before. I solved the daily puzzle once, and when I revisited it it didn't change my rating even though I completed it.