I started a krastorio/space exploration map with AAI Industry yesterday.
Now I have a total power failure as the AAI/I processed fuel is no longer accepted to be burned - not in furnaces either.

Is this intended behavour or an oversight in the recent krastorio2 update?

I also have same problem as well. I not sure if newest patch makes that way. I checked changelog, nothing about that. I was assured it is bug unless it is intended.
Edited: I not use space exploration mod though. I use Only K2 with few smaller mods such as Squeak Through, and Alien biomes and AAI-industry of course.

Is intended, disable the option to rebalance fuels to return to the normal beheviour

Alright, Thanks for your reply, after I disable rebalance fuels, auto game restart, open same save as before, I discovered same problem as before, even tried feed directly to boiler, burner inserter and furance. Well, I guess not big deal at this moment, learn and adapt is my motto. I love your mod though!