Campaign Score/Time/Difficulty Not Registering

I have been trying to complete the campaigns on legendary, but about half the time it seems like the level completion fails to be counted (heroic portrait for the level remains from previous level completion, without updating the level to the legendary portrait). Similarly, my level scores and times often fail to be counted. For instance, today I had to repeat H4, Level 5 (Reclaimer) on legendary to get the portrait to update, despite beating it last week on legendary. Also, I just completed H4, Level 6 (Shutdown) and had a score well above the par score (25,000), but I did not get the achievement nor did the friend’s score table update with the score. The legendary portrait did update, however, no score was added to the friend’s score table. Also the “Explore the Floor” achievement failed to pop during that run as well. I tried again but this time on Heroic instead of legendary and this time my score was well under par, but my time was much faster than par, and I made the Hunter fall to its death for the achievement. Again, no achievements popped but the friend’s score table updated with a score that did not seem to match the score I achieved during either of the 2 attempts.

Does anyone here know what might be going on? Maybe an internet connectivity issue? I did have the non-scoring skulls on, but none that were x0, and I have had them on in several completions where everything worked as it’s supposed to (portrait update, scores recorded, achievements granted), so I don’t think that’s it but I could be wrong.

Update: I also seem to no longer be getting achievements at all, even though earlier today I was able to unlock one and had not turned off or restarting my gaming session (so I don’t think it’s an Easy Anti Cheat -related issue, but I’m just guessing at this point). Now, even though acts that should both be counted as work toward a weekly challenge and unlock an achievement, only count toward the weekly challenge and do not unlock the achievement (e.g., I got the Bandana Skull on the Halo CE, Level 4 (Silent Cartographer) and it updated my progress on this weeks challenge to collect 5 terminals/audio/skulls/etc, but the Bandana Skull achievement is still locked.