Yes, RCS works just right, it looks like it's just the switchable options for the standard fuel tank.
I spotted on github that PP has had compatibility changes in the TankContentSwitcher.dll for 1.3. I'm a bit of a noob with C#, could this be related? https://github.com/Starwaster/ProceduralParts/commit/98b9fd6a3df2f728f1ab7c2996b27b1162b6022