Ever111, I am saying that both sides of the beam location would have to have been equally supported assuming that there was no preexisting deflection of the story above and it were level, bracing those two sides of the second story floor joists would have sufficed. However, If there was already sag in the second floor and only one side of the beam (say the far joist run were supported, the top plate left behind would not have provided sufficient support to the near side joist run which bears upon the removed bearing wall, prior to the installation of the beam and would have allowed for additional sagging of the near side floor joists during the wall demo and subsequent header beam installation. In other words, both sides of the beam would have had massive weight upon those temporary supports and would have compressed the texture on both sides of the bearing wall, IF properly supported at a level plain.
you say that there was material above the header beam, is there a visible gap between the beam and the top plate since you have removed some of the drywall above the header? how much of a gap is there?