And one at 87%, too.
Other details:
- This is the only upgrade I've had this issue with. I had it a couple of times in the previous galaxy, but I think it fixed itself after a few turns. I'm working on a much bigger scale this time around so it's manifesting more, but it's not going away this time.
- Two of the planets on that list (Jansamei and Horcrux) successfully completed construction of Regional Government upgrades while stuck at 83% on the power planet. This suggests it's not a resource issue. Also, those two are not among the ones with slightly higher completion percentages, which suggests my initial theory about the percentage being tied to actual power consumption is incorrect. So yeah, it does look like a bug.
- None of the planets in question are actually receiving any benefit from the power plant, so it's not a turn report bug.