Mod Version: 1.11-1.1.0.8

(Ex.) Take diamond pipe, place it, then break it. Your previously diamond tier pipe is now stick tier.
This happens with cobblestone, iron, gold, or diamond pipe.

Thanks for reporting!
Only because the color was incorrect, it did not become a pipe of stick so you can play on the world you played in 1.1.0.8 or before.

Sorry, this doesn't seem to have fixed the problem. The pipes look better in JEI, in inventory, and when holding, but I don't think they render the different tiers in the world.
Back to my example I take a diamond pipe in my inventory and hover over it and press R (JEI Show Recipe) and it shows correct diamond recipe. I then place it, break it and pick it up. This doesn't put the pipe back into my diamond pipe stack in my inventory. It makes a new stack, or if I have stick tier pipes it puts it in that stack and when I press R to show the recipe it shows stick tier. It also goes from rendering the nice diamond tier in my inventory to rendering as stick tier in my inventory after I brake it and pick it up.

I didn't do enough tests ... I'm sorry.
This time it was fixed. Sorry about the expensive pipe you put.