Furnace not working after LP Fillup

I had that same problem. Now when I hook up a new tank I just barely crack it open and leave it for about 5 minutes then open it fully. No more problems!

yes, do the same as you do, not a problem, thats the way it works.

I ran into this problem a few weeks ago. They let the tank run out of propane. I could not get heater to come back on. Turned swith off and on for heater and it came on. Worried me as we would be away for a week from rv. They had it set up where they could turn on one of trailer tanks while filling aux. Tank. That would keep propane to heater. If they did not do that like they did that one time heater would not come one. Just a wierd thing that must be watched.

Many tanks have all the safety stuff in them that shuts off the flow if the gas flows too fast.
Long shot perhaps, but maybe when you turn the gas on it "thinks" there is a fast leak and shuts flow off.

Try turning the valve on s l o w l y and see if that works.

Also make sure your hookup connection is good. Make sure the hose is well seated in the bottle.

Two thoughts here.

1. Normally, I can "purge the lines" by lighting my stove top for 10-15 seconds.

2. I'd suspect you have a regulator that is not up to snuff.