I went to Menards tonight after we filled the tank with gas, so that I could get a fill on LP. The girl screwed the nozzle on the fill port and pulled the trigger, gas shot out the vent, so she tried ...
It looks to me like the person filling the propane tank was clueless. In all probability the bleeder valve was already open and when she began filling gas began coming out...just as it should until liquid begins coming out at 80% full. Suggest you take your MH to a filler who knows what he/she is doing.