Black Mouth When Loading A Specific Look

[BritishScenes]

Hi All,
First time poster incredibly long time lurker,

I have a issue when loading a specific look that I have created, the mouth of the model is black inside, I don't have a mouth texture applied but if I apply one It doesn't show.

the skin used is RenVR Original Keya, if I apply a default skin the mouth appears.

I have cleared cache, reloaded the Keya skin and also redownloaded them incase they were corrupt.

any help appreciate it's holding up me releasing my first scene