If you're having issues creating a character, clear your cookies and log in again. If you continue having issues, contact us.
I pull up an entry "poisonous snake" from the MM1 (which I have purchased in Roll20). When I grab the creature and pull it to the TT, nothing happens. It doesn't place a token onto the table for me. I pulled an alhoon from Volos Guide and I got a message about experience from my xp script. and it rolled hp for the alhoon and after about 45 seconds DID pull him onto the VTT.
There were some issues earlier with the servers, possibly it was taking a long time? I just tried it from my copy of the Monster Manual and it worked. Be sure you're dragging the name to the table, not the icon: