So when the camera was attached my RPI appeared to be picking up the device as ( Bus 001 Device 003: ID 04b4:6572 Cypress SemiConductor Corp.
Should note that the ASI1600MM Pro has three USB ports, two USB2.0 ports (which are usually used for connecting a Filter Wheel, Guide Camera etc...), and a high speed USB3.0 port to connect the camera to the Pi (either directly or via a Powered hub).
The two USB2.0 ports are effectively a USB hub, and I would hazard a guess that the 04b4:6572 device is that USB2.0 hub.
It's not clear why you could not see the USB3.0 device when connecting through the hub, but I would put it down to power and/or initialisation issues. At least you've found a way to get everything working now.
I'm not very good at working with a PI4 as it is all new to me and you may be correct that the Pi4 was initially picking up the USB 2.0 hub on the camera.
The bit I don't understand but I'm glad it works is the fact that prior to plugging my camera directly into the USB 3.0 port on the PI4 it would not work via the powered hub, it appears the Pi4 could not recognise it however after connecting the camera directly to the Pi4 via the USB 3.0 port and getting it recognised and working properly I can now plug it into my hub and it works.