One single letter in this text box will not stay bold

A single letter in this text box refuses to be bold (the second "c" in Death Certificate). It appears to be bold when I click in the text box - but as soon as I click out of it, it goes back to non-bold.

I have tried retyping the entire sentence in a new text box, and the issue persists. I have try rasterizing the text, and the issue persists. Also tried converting the text box to a smart object, no dice.

Can anyone help with this, I am going insane.