When using a custom category provided by a mod, empty categories are shown, see the attached image.
As a test, I used Janitor's Closet to filter out all other mod, in that case it worked, but only after going back to the normal part list and then selecting the custom category again.
Expected:
Actual:

When using a custom category provided by a mod, empty categories are shown, see the attached image.
As a test, I used Janitor's Closet to filter out all other mod, in that case it worked, but only after going back to the normal part list and then selecting the custom category again.
Expected:
Actual:
