Thank you for reporting that issue. I would like to ask you for few more details if that is possible. First od all I would like to see output of the command (when issue happens):
ls -lR $HOME/.config/lxpanel/ Another this I would like to know is content of few environment variables such as XDG_CONFIG_DIRS and XDG_CURRENT_DESKTOP And last one thing I would ask you if your panel uses default command line options from installed file, please.