When I upload by file to the builder I see that the thumbnail looks 100%. When I open the file in the editor, though, the texture is smaller, distorted, and seems to have the texture edges extrude/expanded vertically and horizontally.
A screenshot would help. I think you should check your Weight Paint in Blender, and perhaps - perform a Mesh Cleanup > Merge by Distance at 0.01 in Edit Mode. To me, it sounds like the mesh “explodes” a little bit, and this is due incorrect weight painting. The difference between the Thumbnail and the Editor is that the Armature becomes active in the Editor.
Ah MetaTiger, thanks for always helping me!
Attached is the texture in blender, thumb, and in editor
Looks like a wrong weighting. If you don’t know what I’m talking about check some Tutorials about correct weight painting. Is this a shoe, I can’t recognize it?
I’d try to paint the Object to the closest bone (if its a shoe for example the Feet bone) in Weight Paint Mode and with Brush Blend: Add, Radius: 500, Strength: 1.0 and Falloff: Constant to paint it completely red to see if it helps. You should also paint all other Vertex Groups with Brush Blend: Subtract to appear completely blue that only the red painted Vertex Group affects the Object.
Look at these two screenshots of my Peace sign wearable. The sign follows the movement of the spine bone: First screenshot shows full weight = red which means it will follow each movement of the selected Vertex Group Bone (Avatar_Spine) and second is no weight = blue which means it will not follow at all.
For a more precise weighting you can paint the color steps between them with a lower Strength (Screenshot 3), but this needs a lot of experience or try and error as the painting of other Vertex Groups and the whole “orchestration” also affects the movement, too. That’s why you should focus on one Vertex Group first.