Yes, this is expected. Phi needs to be sorted because the values of phi should be in ascending order.
Initially, phi is defined from 0 to 360 degrees and on rotation by 90 degree, the initial value changes but it also introduces a zero value for some of the elements because of the rotation. Hence, the values of phi need to be sorted in ascending order, so that they match correct values of gain and theta.
If the values of phi are between 90 to 180 degrees, rotating it by 90 degrees would make the values of phi to be between 180 to 270 degrees and that would still work albeit you apply the same effect on the gain and theta for correct results.
I hope this makes your understanding better!
