After installation of the mod, vanilla doors place in 2 pieces, one of which doesnt render except for the collision box, making it virtually impossible to open and close the door or be usable.
using version 3.2.5 DEV3 with forgemultipart 1.7.10-1.1.0.296-universal

I'm not able to reproduce your error, but I did find the hidden door has a handle rotation problem. If you mean't the real vanilla doors that have this problem, then it's definitely not this mod. That's more in the realm of FMP because it does edit vanilla blocks to work it's magic. It could also be Optifine. The only way to find out is to narrow down the cause by removing things 1-by-1. Let me know your results.