• Minecraft: 1.15.2
• Forge: 1.15.2-31.1.77
• CompatLayer (only if on Minecraft 1.10 or 1.11):
• McJtyLib:1.15-4.1.0-beta
  rftoolsbuilder-1.15-2.1.2-beta
  rftoolsbase-1.15-1.1.1-beta

builder does not work beyond 300 blocks
video - https://mega.nz/file/Gs8DXDrY#nAznyH4eQTHTDNWcA0INi5EifjGBqqF28oSFHZJc-Ts

used to work fine

Used to work fine when? What changed?

on previous versions.
but rollback does not help

What previous version. And if rolling back doesn't help, it likely didn't work.

I do not know

I doubt this worked before. The 1.15 version simply doesn't have chunk loading yet. This is something that will happen at some point. I'll keep this open as a reminder that I have to do it

That probably has to do with chunkloading. In 1.15.2 the builder doesn't chunkload yet (I still have to implement that)