Lattice Environment Rendering issue With Mod Installed (1.39.1)

[Sonoluminn]

Issue: The lattice environment's cubes' inner sides when float fx is applied are shaped oddly, with the shape being an inverted bottomless square funnel shape (shown in attached images). It doesn't seem to matter what settings you apply with the mod installed, the fact that the mod is installed itself is what breaks the geometry.
Steps to Reproduce:

1. Download the latest version of Custom Backgrounds for 1.39.1 on BSManager (1.2.2).
2. Launch the game, go into custom background's settings, and disable its ability to show while playing.
3. Play a map using the Lattice environment (I used LILAC for screenshots).
4. Bug
   Expected Results: The inner side of the cubes should be flat and aligned with the outside of the cubes.
   Actual Results: The inner side of the cubes deforms to look akin to an inverted bottomless square pyramid shape.
   
   
   

[Redageddon]

Are you on version 1.39.1, or 1.40?

[Sonoluminn]

Are you on version 1.39.1, or 1.40?

1.39.1 (it's in the title)

[Redageddon]

Just double checking. That is really really strange.

[Sonoluminn]

super strange indeed, it is on 1.39.1, if you wanna contact me on dis for more info its in my profile