Why did Leviathan memory fragments revert to C-class this morning?

Had a great time overnight amassing some X-class mods and hoped to continue that this morning, and maybe see if we could finish loop 5 and get some inventory upgrades, but when I turned in a bunch of ancestral memories I wound up with 45 basically worthless C-class fragments. Also noticed that the "loop progression" mission that tracks loop progress is gone, so I guess for the last day we're suddenly not allowed to progress it anymore? Wtf?