texturemaptocylinder always removes seam (5.6.x)
- Create a cylinder.
- Increase it's resolution to something less blocky (20 works)
- Apply a the 'texturemaptocylinder' filter with an appropriate image. (An earth map works well).
- Uncheck 'prevent seam'.
The image will display on half the cylinder, and then repeat on the other half inverted as should only happen with seam prevention.
To upload designs, you'll need to enable LFS and have admin enable hashed storage. More information