Sorry for the delay on this. The answer is actually simple. Since the dollar sign is a special character for PHP (it defines variables) and all title and descriptions in the captions of SIGPro are parsed by PHP, this special character is seen as an empty variable and replaced with nothing. You have 2 solutions here:

a) Either escape the dollar sign, in other words, instead of just writing $ write \$ (that's a backslash before $).
b) Use the HTML equivalent for the $ which is " & # 3 6 ; " (without the double quotes, and no spaces between characters)

I'll make sure we document this in SIGPro's documentation page until we find a permanent solution to skip the PHP parser when the captions are read.