blockbuster.steve model morph uses 64x32 (pre-1.8) skin format, while blockbuster.fred model morph uses 64x64 (1.8+ with skin overlays) skin format. In addition, blockbuster.alex is basically like blockbuster.fred but with 3 pixel wide arms.

This section of commands page could be useful if you want to convert your Minecraft skin between these two formats (steve and fred).

Unfortunately, there is no way to fix it.

The problem is mod incompatibility between Metamorph and MPM mods. You can fix it by watching and following this video.

Well, there are two possible scenarios:

Depending on the way your model looks like, let's take a look at this exhibit:

• A. INCORRECT: 64x64 skin was used with blockbuster.steve (which supports only 64x32 skins)
• B. CORRECT: 64x64 skin was used with blockbuster.fred
• C. INCORRECT: 64x32 skin was used with blockbuster.fred or blockbuster.alex (which support only 64x64 skins)

The fix for this is to change the model. Either reconfigure the morph from scratch, and give the correct skin, or edit the morph, and just pick another model like shown here:

If that's an issue that arises only with BSL based shader packs, then the solution is to disable an option Visual > Resource Pack Support in BSL's/Complementary's Shaders Options:

If that didn't help. Try also disabling Visual > Normals & POM Config > Parallax Occlusion Mapping.