My daughter has an 05 Monaco that had the same problem. Last year they went to move it and it would no move, first into D then R, no go. They had a tech come up to there place and after an hour or so got it to move. Then they headed to Arizona from Alaska, after setting for a week or so same problem. When they got home in April they took it in Kenworth, problem the brakes and drums were glazed, new brakes and rear drums problem solved.
2006 Country Coach Inspire 360 40ft Genoa Designer Series, Samsung 197 RR
Cat C9--STEEL & COPPER Bolt Together Radiator w/ updated rubber mounting
SilverLeaf 330 Magnum 2812 PSW 2011 Ford Edge Sport-Air Force One