My experience with this proxy server is very limited. Support was originally added based on information that was provided to me by a end user, similar to the post you provided. The solution that was originally added work for this user, but there may have been some details neither of us were aware of.
I made some changes that should help resolve the problem. You can download a beta release with these changes at
http://download.flashfxp.com/beta/ffxp3.7.8.1333.zip
Simply unzip the file and overwrite your existing FlashFXP.exe
Please let me know if this resolves the issue for you.
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