Is it possible that the models you have right now are leftover from installing the models the normal way? I'm not really sure how the models would still load but not have textures unless the original method was being used as I ran into that problem myself.
Just to make sure the zip is set up properly, the contents and location should be structured as such
- "Sonic Robo Blast 2" (app data folder)
- any intermediate folders or nothing (for the sake of this a single folder called "modelpacks")
- Zip folder (let's call this "kaldrum" but can be anything)
- models.dat
- "models" folder
- KLDR
- KDBONUS
- Any other model folders you might want to include
With the models.dat having the lines you want written out manually (copied from install instructions or other models.dats )within the zip.
Then the command should be "modelpack modelpacks/kaldrum.zip"
with "modelpacks/" being the path to the zip.
Sorry if you already knew all this or I over explained anything, this is to my knowledge how to install this and it worked for me. For the record it is unnecessarily complicated, I don't blame you at all for issues with this. If this is pretty much exactly what you did, let me know but I would suggest taking another look at the zip folder you made to make sure it works properly. Hope this helps let me know if you're still having issues. I'd ask you to send the folder setup but I think the file size is too big for the mb.