Once you acquire the Ion Prism and scan it, exit the save (do not close the game), open the save again, and the Ion Prism now carries no energetical value. Not zero, the energy bar doesn't even appear. The problem carries over to other saves as well.
Also, closing the game causes corruption of the save as a whole - the loading screen becomes stuck at "Prototype Sub - Registering prefabs 100%". It's worth mentioning that the problem did somehow resolved itself (once) - the save loaded and the prism had value once more. However, repeating the process of rejoining the save + reopening the game caused the problem to reappear.
#Ion Prism losing energetical value after rejoin + Save file corruption after reopening the game
wild vessel
Also, it's hard to tell whether those are related, but further down the road more issues appeared with the reactor - it refused to accept fuel. The fuel selection menu didn't even show up, despite me carrying ion cubes and warper remnants.