Imported custom assets have no textures

I recently tried getting some custom made traffic signs into carla using the docker method described here.

After some messing around with the blender fbx export settings, I resolved the problem of not getting any static mesh files at all. Now I can actually import the package into a Carla installation, however none of the seem to have any textures when I spawn them CARLA’s the blueprint system.
The export results in 6 files per prop (1 .uasset and 1 .uexp per static mesh/material/texture). These files are very small though.
Importing my fbx directly into Unreal also creats the three .uasset files (much larger ones though) and the props display fine.

Maybe it is interesting to note, that parts of the props do not show the default checkered Unreal texture, but instead a grainy greyish texture. This same texture (on the same pieces of the prop) also shows for a few seconds when I directly load the fbx in unreal. It is replaced by the correct textures after a few seconds though.

Any help would be much appreciated!

In case anyone else runs into the same issue:

We realized that we were creating our asset package in a Linux based Docker container but imported them into a Carla (0.9.11) distribution running on Windows.

We then tried out importing the same package into a Carla (also 0.9.11) version running in Linux, resulting in correctly displayed signs with textures.
I was unaware that there are platform dependencies in UAsset files or in the packages created by the carla package creation process but that seems to be the case.