SQ-5 Slink-IO-Port Delayed Gain Controls

I thought I’d ask about a scenario here before continuing with A&H support.

I am seeing delayed response when adjusting channel gain via the SQ-5 surface gain knob for channels patched through an SLink Card.

There is a delay of about 1 second from turning the knob to the preamps responding on an IO Box in the 2nd position in an Slink chain
as indicated by the * in the below configurations.
SQ5 IOport (Slink Card) → AR2412 → AB168*
SQ5 IOport (Slink Card) → AR2412 → AR84*
SQ5 IOport (Slink Card) → AB168 → AR84*

e.g. After quick adjustment of channel gain from -20db to +2db on a PADDED channel, about one second passes before audible increase in level

Note that operation is normal (responsive) in the nearly identical configurations of:
SQ5 Built-in Slink → AR2412 → AB168
SQ5 Built-in Slink → AR2412 → AR84
SQ5 Built-in Slink → AB168 → AR84

Thoughts?

BTW: Firmware is 1.5.6 r4043.