Confluence refuses to save page with a certain MathJax inline content

[Former user]

I can't save this inline MathJax equation in Confluence for some bizarre reason:

I_s = e^{-A/B} This works fine:

I_s = e^{A/B}

But if I edit the equation to put a minus sign in front of the "A" and click "Save" in the macro dialog, it shows up as a delaying spinner image, and won't save to the server for some reason.

[Scott Selberg]

Fixed in 3.1.1