I do 3, D+1, 2 all day. It's not that. There's a glitch where your game desyncs if you're pressing too many buttons. The netcode just can't handle so many inputs at one time. Try mashing it out a little less hard.
i need to test this out more.. i have a friend that has the same problem when ever he presses 2 buttons at the same time online. he uses scorpion when this happens, theres a combo of his that ends with a 2 button push