I've see this exact issue using my asi120mm-s and asi178 or asi533. I use the asi120mm-s as the guide camera. Trying the Raspberry pi 4 going to a usb3 hub and then to the cameras. (side note, I've tried otther USB configurations, but still had issues.) This configuration never has worked for me. I could never use both cameras simultaneously without timeouts.
What I ended up using a second raspberry pi 4 for the guide camera and another for the main camera, mount, and filter wheel. Doing this split has always work for me. I have always suspected that there was a driver issue with ASI or a USB driver issue with the Raspberry pi's. At one time, the Pi's had horrible implementation of USB drivers (I am sure that this has been addressed in later drivers). Going to the bleeding-edge kstars or the latest SDK never resolved this issue. I was hoping with my new camera, asi533, things would improve, but bench testing showed that I still timeout/exposure failures and many times it would loop when using a single Raspberry Pi.
If you are interested, I can give you details on how I setup the two Pi's to work with Kstars/Ekos (based upon the article "INDI on multiple devices " by Jasem . Perhaps other's have had better luck, and with those cases I would be interested in their specific configurations.