I have to take a break for tonight, but here's what I've found so far:
@[deleted], for the course https://mylittlewordland.com/course/77674, for the word "querulous":
- You successfully reviewed the word on February 14th.
- You successfully reviewed the word again on March 9th, which achieved a new record of remembering it for 24 days. This means the word shouldn't have shown up again in the "Level up" category until 36 days later (150% of 24), which would be April 14th.
- You successfully reviewed the word on March 26th. This wasn't enough to level it up, since it had only been 17 days since you last reviewed it, which was less than your max time remembering it, 24 days.
- You successfully review the word again on April 15th and April 17th.
This suggests to me to that the words are being leveled up correctly but are for some reason being shown in the "Level up" category before they're ready to be leveled up.
@[deleted] I think the bug that you're running into is probably the same, although I haven't had time to investigate yet 🙂