Did you use any lubricant on the 500 S&W cases?
Normally, with T-C dies for straight-walled cases, you don't lube them, but the 500, being so large, does benefit some.
But don't use too much. Too much lube (on either cartridge) can be bad. If lube gets under the T-C ring, it can come out, dragged out by the cartridge case. When that happens, it is almost certain to break, as T-C is very brittle.
If you use no lube, likewise, the case can drag the T-C ring out of the die through just the friction.
Neither of these is likely, but possible.
Also, make sure the Turret head is in good alignment with the press' ram. Mine was perfect right out of the box, but I have heard that some are not (shifted during shipping? - I don't know if that is possible, but this is what I hear.) It is no big deal to realign the turret ring on the uprights, but check the rotational position of the turret first.
Put a shell holder on the ram. Make sure it is fully engaged and can rotate freely. Put a cartridge case in the shell holder and make sure it is fully inserted. Make sure the fit is close. It is possible to have gotten the wrong size shell holder-mistake in packaging happen.
With everything in place and sitting square, run the ram up to the sizing die and see if it enters the die perfectly (as closely as you can tell by eye) centered. Then rotate the shell holder 90 degrees and do it again, all four points of the compass.
If it passes that test, I would figure your press is in alignment.
(The foregoing is just my seat-of-the-pants advice. Lee Precision might have a more sophisticated method.)
Lee Precision's Customer Service has always answered my emails within one working day. But if I as them multiple, complex questions, the answers are usually partial and often confused. Single straightforward questions get the best answers.
If you got the press and dies from Kempf's, Sue Kempf will be helpful if you can get her on the phone.