Ok, I made a quick test. My MacBook 13 also has only 2 USB-C ports.
I connected thru PPBA and with USB-3 to USB-Cable. This caused some isssues with the cameras. They were both connected but I was not able to collect any images.
Now I switched with USB-3 cable to a USB/USB-C dongle and everything works now and I tested another USB-Hub too.

After that I conneted 3 cameras via PBBA, ASI533, ASI120MMS and the Lodestar with USB-3 cable to a HUB that fits directly in both USB-C ports on the MacBook. Sorry I don't know
how this thing is called, is a simple one from Amazon around 15 Euros. I assume it is caused by the cable.
Can you test with another one?