Also shut both propane tank valves off wait a few seconds the very sloooowly turn them back on.
Since you ran tanks out of gas the lines were empty.
Its VERY possible when you turned the valves back on the fast surge of gas popped the opd valves on the tanks.
Doing the above mentioned will reset them.
Issue's always seem to arise when you run out of gas so try not to run out.
I'm not sure why your rethinking your purchase when your not even sure if this is a equipment failure or operator error.
Goshen is my playground.
The last man standing also has a sharpie