We are also having this issue. The game will not load at all. It doesn't even get to the mojang screen. Then we get a screen that says it encountered an error and had to close. I have restarted the switch, redownloaded and checked for corrupt data nothing works. I'm frustrated because we paid for the game and can't even play. It's been like this for months.
My system firmware is up to date, as well as out minecraft. It still will NOT load in our main players switch profile. Loads fine in all others (3 other profiles)