The workarounds didn't help to improve the situation.
However, the issue was resolved after I changed each account's plan for the time being:
Account A -> Personal to Free
Account B -> Free to Personal
It looks like my Evernote said I used up 10GB only based on Account B's usage.
it's a bit buggy behaviour but I will close this thread as I don't have the time and energy to pursue this matter further. 😅
PinkElephant-san, thank you for your help!