Two line equation not rendered in numbered equation

Thank you for your hard work.
I would like to have a two line equation numbered like this:
$$\begin{matrix} if\ exp(w^e_t-w_t)<1 \ then\ s_t^w=0 \
or\ exp(w^e_t-w_t)>1\ then \ s_t^w=1\end{matrix}$$
(I have also tried the “align” instead of matrix. But the equation editor gets stuck as if it was loading. The equation works (it works in libreoffice, with autolatex, and it shows in preview of the docx2latex) but it never loads a numbered equation. What am I doing wrong?