this is a follow up to this issue.
The issue seems to persist with more complex expressions of the system in which the negative gain is not explicit or is "hidden" in the expression simplified by the octave backend.
Example running Octave 10.3.0 in jupyter-lab (but same result in 11.1.0), with pkg control version 4.2.1+ (latest fix commit included):
The above result shows in the low frequencies a phase of 0°.
The correct value, as wolframalpha shows, should be +180° (or -180°):

this is a follow up to this issue.
The issue seems to persist with more complex expressions of the system in which the negative gain is not explicit or is "hidden" in the expression simplified by the octave backend.
Example running Octave 10.3.0 in jupyter-lab (but same result in 11.1.0), with pkg control version 4.2.1+ (latest fix commit included):
The above result shows in the low frequencies a phase of 0°.
The correct value, as wolframalpha shows, should be +180° (or -180°):