From a practical engineering standpoint, here is my take.

Common pitfalls:
1）The cable presents a load impedance outside the stable region at some frequency, usually out of band.
2）Bias network resonances create a low-frequency path that bypasses the intended matching.
3）Decoupling capacitor placement and grounding of the bias network are common culprits.
4）Check stability over a wide frequency range with the actual load, not just at the design band.

Push back welcome — still validating this myself.