I just ran into an issue that was already explained by someone else here:
http://superuser.com/questions/720846/cygstart-directory-switch-is-ignored-when-using-action-runas
Below I paste contents of above report, from ZeroKnight:
It seems the --directory switch is ineffective when used with --action=runas
when using cygstart. For example:
cygstart --action=runas --directory=`cygpath -wa $PWD` cmd.exe /k dir
The expected output is the contents of the working directory of the
cygwin shell the command was run from. Instead, it outputs the contents of
C:\Windows\system32, the default starting path for an administrative command
prompt, completely ignoring the --directory switch. In contrast, omitting the
--action=runas switch gives the expected output, but obviously not with
elevated permissions.
Confirmed the bug to still exist on my version of Cygwin, which is:
CYGWIN_NT-6.2-WOW64 work 1.7.28(0.271/5/3) 2014-02-09 21:06 i686 Cygwin