I am using Sodium + Quilt loader. Enhanced attack indicator appears to do nothing when set to crosshair in sodium settings; it works normal when attack indicator is set to hotbar.

Just tested with Fabric, also only works when crosshair is set to hotbar in sodium, not a Quilt issue.

I have the same issue but i just found that is because Custom Crosshair Mod conflicting with Enhanced Attack Indicator, so you might check your modpack if there is any mod overhauled the crosshair attack indicator

I do not have time to test currently, however I also use the custom crosshair mod, so I think you are right.