Some textures don't load on iOS

Hi, I have a weird problem.

In my scene there are 24 custom lightmaps baked in Maya and recently I started noticing a problem. About 15 of the textures appear black on iOS, while it's all fine on Android.

The textures are not in my Resources folder, they are imported like this:

• Advanced

• Lightmap

• Max Size - 1024

• Compression: RGBA Compressed ASTC 4x4 block

When I set them to Truecolor they appear fine, but obviously the memory footprint is too big. I think that the compression is not the problem here, because some of the textures appear fine on iOS, even though they have exactly the same compression and import settings.

What could be causing the problem?