Please try this
Start FlashFXP, enter the following raw command in the local browser (ctrl+r)
Connect to the server and press ctrl+w to activate sync browsing and try to navigate to a folder.
Finally please post a copy of the session log with the debug information for us to review it.
I attempted to reproduce your issue several times but was unsuccessful.
P.S. I will make a note that 5.2 is not listed in the drop down on the bug tracker and get it added.