I feel your pain. I was miles ahead in my division then this happened.
Is the league coding broken?

If it's still on the old division you might need to leave, rejoin, and play a game to get into a new division.

it looks like they abandoned the project
They didn't. There was a bug introduced and quickly fixed but that left some divisions in the stuck state.
Staff are looking into that but the method I described can get you into a working division.

If it's still on the old division you might need to leave, rejoin, and play a game to get into a new division.
Does leaving your own division restart your progress? I'm currently on champion and about to advance to legend. If I were to leave my league, wouldn't I just be send back to the start at wood?

If it's still on the old division you might need to leave, rejoin, and play a game to get into a new division.
Does leaving your own division restart your progress? I'm currently on champion and about to advance to legend. If I were to leave my league, wouldn't I just be send back to the start at wood?
No, you'll start in a new Champion division.

If it's still on the old division you might need to leave, rejoin, and play a game to get into a new division.
Does leaving your own division restart your progress? I'm currently on champion and about to advance to legend. If I were to leave my league, wouldn't I just be send back to the start at wood?
No, you'll start in a new Champion division.
Will my 564 points be wiped, though?

still bugged, surprising. Hope the team is actively working on this issue since it impacts many players. Hence, could an official statement be made?

If it's still on the old division you might need to leave, rejoin, and play a game to get into a new division.
Does leaving your own division restart your progress? I'm currently on champion and about to advance to legend. If I were to leave my league, wouldn't I just be send back to the start at wood?
No, you'll start in a new Champion division.
Will my 564 points be wiped, though?
Yes.
I think staff are looking at moving those that qualified to promote but not 100% sure or how long it will take
You might contact support directly
https://support.chess.com/collection/343-contact-us

still bugged, surprising. Hope the team is actively working on this issue since it impacts many players. Hence, could an official statement be made?
For anyone that isn't in a promotion spot, leaving leagues and rejoining will get you in an working division.

yes Martin and restart from scratch... Don t you think this is kind of disappointing? knowing the energy we put to progress in the league... Thank you.

yes Martin and restart from scratch... Don t you think this is kind of disappointing? knowing the energy we put to progress in the league... Thank you.
From scratch in a working division, at the same tier level. Last week's divisions that are bugged had stopped giving any trophies, so there wasn't any progress past that bug happening.

The slow resolution of this bug and the lack of transparency here will be a reason for people leave chess and will go to Lichess (OpenSource project and best issues management)...

I was able to get it fixed by leaving the league, playing a game, joining a league from the leagues page (not the page that showed my previous league), then winning another game. I can tell you that the 24 other people still in the league I left haven't figured this out yet

I was able to get it fixed by leaving the league, playing a game, joining a league from the leagues page (not the page that showed my previous league), then winning another game. I can tell you that the 24 other people still in the league I left haven't figured this out yet
So did I last week (and I already got promoted) as well as almost any other interested in playing the league. I think that many of the 24 players that are still stuck in your former league do not care about the league
The one week where I might have won and this simply refuses to update any stats at all.