This bug was even seen in one of Dire's recent RFTools spotlights, so this shouldn't be on just my side.
Mana tablets do not turn blue, untill completely full.
After it's full, and it loses any amount of mana, no matter how big, or small, it instantly turns back to white.
Relogging doesn't fix this.
Versions:
Botania r1.9-332
Baubles 1.10.2-1.3.BETA9
Forge 12.18.2.2106
Minecraft 1.10.2

https://youtu.be/SGSGou1NHFE?t=610
There's the video that I mentioned, by the way.