The panning in the Tap Delay Submix Effect does not always match its assigned Pan in Degrees value. Specifically, the left and right side appear to be reversed on Stereo setups. In addition, in 5.1 setups, there is an unexpected jump between 44 and 45 degrees, and -30 and 30 degrees appears to be reversed.
When working, the Pan in Degrees should be able to smoothly pan around the listener, with a value of -180 and 180 for behind the player, -90 for direct left, 0 for front, and 90 for direct right, respectively.
Expected Result: The sound will slowly pan around the player, starting from the back of the player (at -180), to the direct left of the player (at -90), to the front of the player (at 0), to the direct right of the player (at 90), then return to the back of the player (at 180)
There's no existing public thread on this issue, so head over to AnswerHub just mention UE-130783 in the post.