It's a bit of a problem, but it might confuse newbies who try this mod.

-Just the editor doesn't rendered correctly.

-Editor doesn't update texture on model when resizing Texture Sheet Size in Skin Settings menu.
(Nothing happens when adjusting numbers.)

-Still update when reloading the model (Save and load the file) or use any 4 button on Skin Settings.

-If using the new skin and do copy old texture and then when the texture is updated the textures are not rendered correctly.
(Like size or position UV not updating and messed up)

-Need to reload the model or use the Open Skin button to fix issues.

-Delete skin sometime not work. If it happens, it must be reloaded before deleting.

-When tested in games, UV and textures always render correctly.
(upscaling and reducing texture sheet or texture skin still work fine).

-GUI show skin UV and textures are still ok.

more info

-File Latest.log Looks good, no errors related to cpm.
-I'm not using any shader mod.
-I don't use mods that modify network packages.
-Tested in single player mode.

-fabric-loader-1.19 (loader version 0.14.8)
-fabric-api-0.58.0+1.19.jar
-CustomPlayerModels-Fabric-1.19-0.4.5a

and i found a problem on the web editor as well.
https://tom5454.com/cpm/editor.html