We have 3 models - Left, Middle and Right. Left and Right uses 3 materials - Red, Green and Blue. Middle uses 2 materials - Red and Blue, like this (screenshot from 3ds Max):
When we import these 3 FBX files by dragging and dropping them into a playcanvas project, Playcanvas almost always assigns materials wrong. With Import Hierarchy and Create FBX folder turned off, it can assign Green where Blue should’ve been on Middle:
… or it can assign Blue where Green should’ve been on Left and Right, and not assign Green at all:
… or with Import Hierarchy and Create FBX folder turned on, it can fail to assign Green, but otherwise work correctly.
It’s not a problem specifically to these models either - I just tried the same thing with simple boxes:
If we import these models again we get a different result, either wrong or right. We may need to hard-refresh the browser (Ctrl+F5) before importing for this behavior to occur.
However, if we import the FBX files one by one, materials get assigned correctly. It’s not really an option though when you have hundreds of models to import.
Here’s a Playcanvas project where I’ve imported these FBX files. Download them and import them agaín to test the import behavior.