Minecraft: Forge
Version: chisels-and-bits-forge-1.3.137
Using rubidium and other fps mods

I can't for the love of my life finish building my project due to some bits not loading, and every time I delete them, the whole block gets destroyed. The only solution to make it so that the whole thing doesn't get destroyed is to rejoin, which is time-consuming, considering I'm using a not-so-fast laptop. I've tried doing F3+A/T yet the bits still won't load. Some bits do their job while some just don't load.

I don't understand your issue. Is it the entire block that won't load? Is it always the same block that won't load? Or how am I supposed to interpret this?