Advancement tabs doesn't exist until at least 1 advancement has been done.

[Nova-Katt]

Minecraft 1.20.4
Fabric Loader 0.15.10
Fabric API 0.97.1
Better Advancements 0.4.1.6

I run quite the number of mods, and many of them have advancement, some of them are very helpful in even knowing how to progress at all in those mods.
However, unless I've managed to gain an advancement in that tab, the tab doesn't exist.
This means I have no idea what advancements exist until I finish one of them...
One of them per every tab.
I can't even see the vanilla tabs before I've completed one of that tabs advancements.

If this is intended, it should be a toggle option to "hide advancement tabs until at least 1 advancement has been completed" instead of default and unchangeable.
If this is a bug, woohoo, then now you know and can fix it. :)

I don't even know which of my mods have advancements or not right now because of the tabs being hidden.

[way2muchnoise]

This is default minecraft behaviour where you have to unlock the "root" advancement before you can see the tab. So just revealing all tabs can spoil some advancement tabs.

Will keep this open as feature request.