THINK!!!
Your "Hot Sustained" (just which paragraph of the Code discusses this load case, by the way?) load case is (W+P1+T1) - T1. Thus, the T1 case has no gravitational force associated with it. I would not at all be surprised to see that some displacements in this load case were very large uplifts. Then you are subtracting these displacements in the post-processor module from displacements generated by an analysis in which gravity is active, and which presumably has weight supports now and then.
HELLO!!!
ARE YOU THINKING YET???
Have you figured out the answer?
If YES - congratulations, you've learned something.
If NO - you are beyond hope and there's no point explaining.
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CraigB