Proper animation of a rollband

Hello, guys!
As the title suggests, I am having issues with the seamless animation of a rollband texture.

I shall first mention that I am using a modified version of the Mercedes O307 rollband script, since it's closer to the desired result than the MAN SD200 script.

My rollband O3D is made of 2 identical meshes in the exact same position, but with different texture files ("rollband.tga" and "rollband2.tga", otherwise identical in appearence) and different mappings (pretty much like this piece of advice suggests).

The texture itself is a 32-bit TGA of quite high-resolution (3000 x 500 pixels - I don't think it's a big deal since the O307 rollband texture is also irregular).

The relevant section from model.cfg looks as below:

[mesh]
rollband.o3d

[matl_change]
rollband2.tga
0
lights_stand

[matl_freetex]
rollband2.tga
Rollband_Tex_H

[texcoordtransY]
rlbnd_ziel_trans_2

[matl_texadress_border]
255
255
255
0

[matl_item]

[matl_lightmap]
multipurpose_LM.bmp

---

[matl_change]
rollband.tga
0
lights_stand

[matl_freetex]
rollband.tga
Rollband_Tex_V

[texcoordtransY]
rlbnd_ziel_trans

[matl_texadress_border]
255
255
255
0

[matl_alpha]
1

[matl_item]

[matl_lightmap]
multipurpose_LM.bmp

[visible]
vis_rollband    <-------- the whole rollband setup can be changed via setvar with a matrix
1

The issue I have is that the smooth transition from one blind to another only happens "halfway" across the width, while the other half switches instantly to the next texture.

I tried to show the behavior in a screen capture which I attach below as a zip file.

2025-10-01 20-56-02_001.zip

Can anyone help me out?

Much appreciated!