How to Fix Athena Mod Not Working (Missing or Broken Connected Textures)
Confirm Athena Is Actually the Problem
When connected textures or custom block models look wrong, the cause is usually a conflict, not Athena itself. First, check that the resource pack you are using actually ships Athena-format connected texture files. Athena only renders CTM for packs and mods that provide the correct metadata; a pack built for a different CTM system will simply show unconnected textures with no error. Load a pack you know supports Athena and look at a glass pane or a stone-brick wall to see whether the seams connect.
Isolate Conflicts
If textures are missing entirely or blocks render as the purple-and-black missing model, another model loader is likely overriding Athena. Run the game with only Athena plus the mod or pack you are testing. If it works alone, add your other mods back in small batches until the breakage returns — that batch contains the conflict. Pay attention to other connected-texture or model-loading mods, since two systems fighting over the same block is the most common failure.
Check the Obvious Settings
Make sure the resource pack is enabled and sits above any pack it should override in the pack list. Toggle the pack off and on again to force a reload, and if problems persist, restart the game rather than just reloading resources. If a specific block type misbehaves while everything else is fine, that points to that block's model or CTM definition rather than a global Athena failure.