Rank fight level gets lost again and again (Splatoon 2)?

Recently I was in the ranked fight mode and reached level C, the next day the C rank was still there, I played a few rounds and then switched to Bär GmbH, when I came out of Bär GmbH again, I was ranked in rank fight gone and it was back at rank C-, it has happened a few times that I have to start all over again, what's the problem? Does Nintendo not save this data, or is it preprogrammed in the game that you have to start over and over again?

Did you possibly lose laps in ranked? This can cause you to lose your rank or relegate

So there was a crack and then at some point I switched to Bär GmbH

Was it still the same rank fight mode? The rank is independent in each mode.