Since June 10th, I have been experiencing a significant increase in "Service Unreachable" warnings while uploading 2K PBR materials exported from Adobe Substance Painter using the glTF PBR Metal Roughness workflow.
The problem seemed to be concentrated between June 10th and June 12th, then improved and became limited to just a few random errors.
Today, June 25th, the problem is back on my end.
I have checked my internet connection, restarted my fiber router, and confirmed that my connection is stable, yet the issue continues to occur.
I can log out and back in, successfully upload one material, and then immediately receive the warning when trying to upload a second one.
If I bulk upload an entire material set, some materials upload successfully while others fail. Sometimes the material upload window gets stuck trying to save, and I can't close it because it appears to still be processing one of the texture maps. At that point, I have to relog.
This issue seems to happen much more frequently with 2K textures. Since my UVs are optimized for that resolution, switching to 1K is not a practical workaround.
Normal maps seem to be affected the most and fail more often, but on days like today I'm also getting errors when uploading base color and metallic-roughness maps.
I know there have been previous posts about this issue, but I believe it continues to resurface and may still require investigation.

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