The exception occured when teleporting between 2 bases and having embeddium installed, it caused chunks to stop loading due to a ConcurrentModificationException and leaving a hole in the world for me it was a 3x4 chunk hole with 2 chunks containing rotor shafts and blades.
This only happens when a rotor shaft/blade has any shaft or blade connected to it as shown in the screenshots below .
The setup:

After teleporting to my base and back:

After teleporting 10000 blocks away and back:

The last 2 screenshots are of a new world in a modpack with only ExtremeReactors and Embeddium.
This weird behaviour doesn't happen when first loading into the world but only after having the chunks loaded, teleporting away and then back
The only fix I have found so far outside of just breaking the blocks and teleporting back and forth again is changing dimensions, sometimes really slowly approaching the area works too but that doesn't always work.

Game logs attached:
2024-10-12-1.log