Missing Thumbnail for modular stairs

Ok, I hope this is the right place to ask. I have some modular stairs from Aviolinas Silent Hill set.
The stairs are fine to use in game (with railings and all) but they don't have a preview-thumbnail in the catalog (or next to the description-which shows up)
It's not a cache problem I checked that several times and they never had a thumbnail to begin with.
I looked into the cres files under the thumbnail section cause I read that deleting the line there can help with thumbnails showing up wrong (which worked for me in on other occasions). But there's nothing written in that section. (Items list is empty)
Originally there was no textfile for those stairs (for the scriptsfolder) so I copied an existing one and adjusted the values. Did that with other stairs before just mentioning it in case that could have something to do with it.

Mediafire link to my stairs file

I don't even know where to begin looking I have little to none modding skills. I'd be happy for any help you can provide.

P.S.: Other people added download links for her full set here and here I took that as validation that it's ok to reupload my file too.

Edit: Just in case someone knows Aviolinas stuff I'm not talking about the consolation stairs that have already been redone/repaired by exclectica/curiousb