My '84 Jeep has had this problem for a long time. If it sits for more than a day, the transmission will not engage any gear at all upon first starting the engine.
However, if I shift it back and forward between Drive and Reverse about 5-8 times after the engine has started, it will then engage a gear and perform flawlessly for the rest of the day.
It has been doing this for the last 30,000 miles or so.