About the IMC: the IMC is lock-cycled on purpose during FmodErr if the PZT correction is outside thresholds; if it does that very often, that could point to an issue between the PZT and the IMC length driving. Maybe it has a common cause with the fact that the IMC unlocks frequently while scanning for the RFC resonance, as "big" movements of the cavity length are done in the process.

About Lock Acquisition: all the phases should be restored, we can relock to LOW_NOISE_1 but the PR loop (in DF) should be re-checked, as it was not working properly; I removed the 150 Hz notch as it often killed the lock in DF; PRCL_GAIN for dark fringe is strangely lower than usual. To be checked.