Power supply problems
From the comments, the V-drop is ~35V. This is a huge V drop for those regulators. You're probably over heating them and triggering their thermal shutdown mechanism.


Reduce the input voltage as close to +-45V (Plus drop out voltages) as possible.
Add heat sinking to the cases suitable to the anticipated power dissipation. (remember to add the sense resistors in, they consume almost 1/3W by themselves)


Edit: Took out my guesses. Added clear suggestions