The render layer is not set back to its original value in the TESR, which corrupts the states for further renders (items).

See Chisel-Team/Chisel#404

You should probably reset the state here https://github.com/McJty/RFTools/blob/1.11/src/main/java/mcjty/rftools/blocks/elevator/ElevatorTESR.java#L69

Additionally, you make quite a few draw calls in that renderer when it should only be a few, batch all blocks for a given layer together to save. Better yet, use FastTESR

I will check this out soon

One question. Is using a FastTESR a good idea for a moving object? If there are many other FastTESR's in the vicinity it will cause them to recalculate all together with every frame that the elevator moves

Hmm. How can I restore that state? I see no getter for it. There is a setRenderLayer() but no corresponding getRenderLayer()

Should be fixed next release