Seem there is another bug in the .Net regex engine concerning Unicode

The characters matched by the Unicode categories for quotes are backwards.

Pi – InitialQuotePunctuation Indicates that the character is an opening or initial quotation mark. Signified by the Unicode designation "Pi" ( punctuation, initial quote ).

Pf – FinalQuotePunctuation Indicates that the character is a closing or final quotation mark. Signified by the Unicode designation "Pf" ( punctuation, final quote )

However \p{Pi} will match a closing quote and \p{Pf} will match an opening quote. This is backwards. 

I should note the quote characters in question are the Unicode left and right ‘single’ and “double” quotation marks not the ASCII double quotes (") or apostrophe (')