The bug tracker searching engine does not work properly

Mojira websites (bugs.mojang.com and report.bugs.mojang.com) are often buggy and slow. There are some issues that I’ve encountered:

• Switching to “Done issues” gives empty issue list (it might be being caused by a random event).
  Expected: A list of all issues that are not open (e.g. fixed, done, invalid, duplicate).

• Changing the filter settings can sometimes keep the issue list as it was.
  Expected: It should update the list so that it satisfies the filter settings.

• The interface doesn’t inform about the REST API failure (500 code).
  Expected: An error message should appear on the screen.

• Sometimes, a loading animation (spinning circle) shows on report.bugs.mojang.com for more than 1 minute despite having a good internet connection, and a list of bugs doesn’t appear.
  Expected: A list of issues with default filter and sort settings.