Looks like the selectbox in the power stations is not accessible anymore? Can you have a look at it?
So I am not alone… 
Reproducable from a SaveGame and in a new game…
When you try to upgrade there is no button to click… 
Same issue. Ironically if you research power plant efficiency you’ll get it automatically on the power plants already installed, but never on future ones.
Looks good in 1.36 to me on the savegames
Yup, should be fixed in 1.36, thats only on steam at the moment, but will be everywhere with the next update.