ZWO were suggesting it was a USB bandwidth problem but USB 3 is pretty fast and even having the cameras on different busses, the imager on USB3 and the guider on USB2 didn't help.
I also had instances when the guide camera would stop working completely and only a disconnect/reconnect would make it work again.
The debugging from the indiserver is a bit confusing, plus the information is being truncated making it hard to understand what's going on. The ASI ccd driver debug is a bit clearer - you enable it by modifying the ~/.ZWO/ASIconfig.xml file to set <DebugPrint type="3">01</DebugPrint> and the log file is in ~/.ZWO/asicamerasdk/asicamerasdk.log
Here's an excerpt
2021-07-15 21:22:30,997: INFO ASICamera : [WorkingFunc]: head:0xaa11 tail:0xf200
2021-07-15 21:22:30,997: INFO ASICamera : [WorkingFunc]: drop frames:4
2021-07-15 21:22:31,048: INFO ASICamera : [AutoExpGain]: Dest:100 Mean:1 gain:50 exp:95000 reg:0x43a
2021-07-15 21:22:31,152: INFO ASICamera : [AutoExpGain]: Dest:100 Mean:1 gain:50 exp:95000 reg:0x43a
2021-07-15 21:22:31,231: INFO ASICamera : [WorkingFunc]: head:0xaa11 tail:0xf200
2021-07-15 21:22:31,232: INFO ASICamera : [WorkingFunc]: drop frames:5
2021-07-15 21:22:31,232: INFO ASICamera : [WorkingFunc]: try lowing pkg!!