Odd behavior between translucent materials, scalar parameters and the barrier device in performance mode

General Issues and Bug Reporting
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1

Please select what you are reporting on:

Unreal Editor for Fortnite

What Type of Bug are you experiencing?

Assets

Summary

When using a custom material with transparency in a barrier device the material goes fully opaque after walking toward then away from it.

Steps to Reproduce

Create a material
Set the blend mode of the material to translucent
Create a scalar parameter named “Opacity”, connect it to the opacity pin of root and set the scalar parameter value to 0.5
Apply custom material to barrier device
Push changes/Launch Client
Set client to performance graphics mode
Observe translucency is correct on barrier
Approach barrier until it completely fades & culls
Move away from barrier and observe the material is now opaque.

Expected Result

Material returns to opacity value set by custom material.

Observed Result

Material obtains full opacity after moving away from it

Platform(s)

PC

2

Just want to add the workaround is changing the scalar parameters to fixed values. However this eliminates the possibility to instance the materials.

3

I just tried a vector parameter and that works fine.

The bug lies solely in the scalar parameter node.

4

I further narrowed it down to this - Having a scalar node with the name “Opacity” causes the bug.
I am assuming it is conflicting with a baked parameter with the same name.
Renaming the scalar parameter to “1 - Opacity” fixed the bug.