OK, I've replicated the error from your scene.
Before I explain the fix, I want to point out that the file units should be set to Generic instead of US Standard. This is not related to the current issue, but I want to make note of that before I go further.
There is a default value of size of 64x64 on all brush faces at export time. During the export WW looks up for the actual dimensions of the bitmap on faces to override those defaults and set the correct scaling. Any bitmap that is not found will get that scaling.
The odd thing here is that the bitmaps are obviously available here. For some reason Max is telling WW that the bitmaps are undefined. I do not know yet if this is bad logic in WW or a bug in Max. In any event, here is how I got the scene to export properly:
- Click File > References > Asset Tracking
- Select all the bitmaps in the list
- Right-Click the Make Path Absolute
If the Make Path Absolute isn't available, then first make the paths relative to the project folder first with the same right-click method above, then the Make Absolute will be available.
I am going to have to investigate this issue with relative paths.