EDIT Solved via lxqt going to 0.11, was mostly a heads up here end edit
Not often that a bug hits testing but not sid. For those of you who have just "dist-upgraded" you LXQT on Sparky (or vanilla Debian testing) your pcmanfm-qt crashes easily.
If you have been bit by the debian BTS but #842080 - it should not be out in the wild long. Either grab from sid or wait a short period of time. I am temporarily using gnome-commander myself.
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=842080
peace out.