I stumbled across this bug while playing the demo version of Alpha 12.
* I purchased 5 imps taking my mana down to 68
* I placed an eyeball lowering my mana to 58
* I ordered the construction of my first library in order to use my spare mana to buy crafting sooner
* Library menu displayed that I had 11 mana (I assume mana that my keeper earned from studying) while the hud showed 60+ mana
* I saved the world and reloaded to see if that would fix them issue, the issue remained (pictured)
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* I then saved and reloaded the world to find the issue somewhat rectified because my 60+ mana in the hud had disappeared and was replaced by 11 (pictured)
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So basically I've had 60+ Mana simply dissapear after building a library without researching anything or hiring any extra imps, not a terribly major bug but it was an inconvenient one.