Forge Ver:
14.23.5.2859

Mods:
aether-1.12.2-v1.5.3.2
Loading-Progress-Bar-v1.0-mc[1.8-1.12.2]

Reason doesn't show a loading bar while still on the Aether tips loading screen. If you disable "Aether Trivia" in the configuration, it shows fine and working. This could be minor bug.