When it happens to me, usually after my game crashes and I am trying to get back into the game, if I hit send and close and restart the game it will usually start, send and restart never works for me anymore- since the last patch. Hope you can get back in the game soon.
Same for me. Someone suggested that it was because my character was in a certain area near what used to be called a node line. I tried a different character in another area and I can play it.
Not sure if a GM can move your character for you to try another area, Might be worth asking.