Data Blueprint Strange Glitch

In my project the FP Gun shows up under mesh, but it is empty and uneditable:

When I drag this blueprint into the editor it also has an error with the FP Gun mesh:

But the old character from this blueprint that existed from the start still works normally:

This project was started with the C++ first person template and then some changes were added to it. I attempted to change the skeletal mesh weapon to my own weapon model in both the character class and the data blueprint then I attempted to revert to the old project mesh.

Hello,

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Thanks