I also had this issue, I was still able to log in to the zero hours and blank avatar, and by sleeping I was able to overwrite my save and bring it back to coop. The progress had saved though we got a connection failed, and it had progressed to the next day in game. However, when I went to the community center I noticed my progress had been wiped. I was able to access the first bundle, but before the glitch, I had four open and some of the bundles complete (though, none of the rooms). I just switched to a different season, so getting the spring bundle stuff, even with my hoarding in case quests or issues arises, will be quite a pain.
I’ve had the blank avatar twice, the first time I deleted it thinking it was just a glitch and lost my coop world, and the second time I overrode my data but lost my community center (that’s the only major loss I know of so far).
I also have the connection failed bug quite often and we have to restart that day, I can’t tell if there is a trigger but it doesn’t seem to be the case. I hosted and my friends have hosted, and all of us have had the connection issue and every time it seems random.