Before following this guide you will need to make sure you have the changes from this previous update, this change was made in SGK version 2.3.5 if you using a newer version then that you will already have the changes in the guide linked below.

https://defusestudios.com/sgk-v2-fixed-floating-weapon-in-first-person-reflections-ue5/

Add the highlighted nodes shown in the image below, location at the top of the image.