A few people have had this problem... Nobody knows what causes it, and as far as I know everyone does something different to fix it. You could try several things:

1) Import it with a random name just to check (i.e. "aswefjaskdjgaksgja")
2) Verify the integrity of the game cache files for TF2 and retry the import process
3) Delete your workshop files locally (or move them out of the steam folder) and retry

HellJumper の投稿を引用：

A few people have had this problem... Nobody knows what causes it, and as far as I know everyone does something different to fix it. You could try several things:

1) Import it with a random name just to check (i.e. "aswefjaskdjgaksgja")
2) Verify the integrity of the game cache files for TF2 and retry the import process
3) Delete your workshop files locally (or move them out of the steam folder) and retry

None of those worked

Same thing happened to me when I first tried. If you're sure you got all of your import files deleted (and I mean the .zip file folder locations AND the .mdl previews) then also try renaming your item title. However, the importer may still remember the previews, I think.

For example, when I test import the items to check in mdl, I give it an intentionally fake name so I know it's not my final (Castlington). Once I know the parts are working, then I name the full file what I intend. I suspect it's not just the .zip files that matter, but those previews as well, though. For you, the renaming it (Cast_Away vs. The_Cast_Away) may jump past the bug.

Hopefully I'm not misinterpreting HellJumper's suggestion for step one... I was thinking he was referring to the file part names being imported renamed. We may both be referring to the title of the .zip. ;)

Finnigan の投稿を引用：

Same thing happened to me when I first tried. If you're sure you got all of your import files deleted (and I mean the .zip file folder locations AND the .mdl previews) then also try renaming your item title. However, the importer may still remember the previews, I think.

For example, when I test import the items to check in mdl, I give it an intentionally fake name so I know it's not my final (Castlington). Once I know the parts are working, then I name the full file what I intend. I suspect it's not just the .zip files that matter, but those previews as well, though. For you, the renaming it (Cast_Away vs. The_Cast_Away) may jump past the bug.

Hopefully I'm not misinterpreting HellJumper's suggestion for step one... I was thinking he was referring to the file part names being imported renamed. We may both be referring to the title of the .zip. ;)

Nothing is working ;___;