Describe the bug
When I track an advancement and complete it, the tracker doesn't remove it. However, if I relog, it removes them,. But then, after the first advancement completes, it disappears from the tracker, but then anymore newly completed advancements don't. I have a ton of custom advancements, along with 4 starter advancements in the config.

1.16.5-0.2.1

To Reproduce
Steps to reproduce the behavior:

1. Create a Custom Advancement
2. Assign it to the Tracker
3. Complete it
4. It does not remove from tracker.

Expected behavior
I expected the Advancement to be removed from the tracker when its completed.

Screenshots

Debugging
I don't see any relevant in the logs.

If it helps, here are just a few of my custom advancements. Some may not work because of modded items, but this is primarily vanilla stuff.
survival.zip

AH HA, figured it out. It was the screenshot feature messing it up. That's why only the first advancement succeeded. I am playing through Curseforge and my files are saved under Document/Curseforge/Minecraft/Instances. Maybe that could be causing the screenshot feature to hang up the program?

Nope, still doing weird things. Start a new world, advancement disappear when completed. Save and quit, log back in, advancements don't track.

Thanks a lot for the report, I will try to reproduce the issue and will try to implement a fix.

Ok, I think I've narrowed it. This one was hard to nail down. If I don't add any preloaded advancements, the tracker doesn't update. If I add preloaded advancement in default, the tracker will update only for those quests, and not any manually added to tracker. If I add preloaded advancements in local cache, everything appears to work great, manually loaded or not.

Thanks a lot for the additional details. I was able to reproduce the issue mostly in the single player mode and found some issues I need to address.
I need to rewrite some of the logic and will provide an updated version which will fix these issues in the next days.

Ok, this was more complex that I thought, because they advancements event handler are not 100% reliable.

I added several ways and checks to make sure advancements and update are not missed.
But please open a new issue request if you still seeing an issue with a specific setup or compination of mods.