iTunes can't see new ipad pro 2018

I just picked up the new iPad Pro 12.9 256GB (Nov 2018 version) and can't say I'm enamoured with the experience so far. Firstly the screen's flawed and it looks like Apple installed and laminated a scratched plastic screen cover over the liquid Retina display (there's a colour changing rainbow-like mark beneath the surface of the iPad touch surface).

Whilst I considered whether it bothered me enough to return the iPad Pro I thought I'd set up the device and selected 'Restore from iTunes Backup' which takes me to the screen asking me to connect the iPad to iTunes, which I've tried to do for 2 hours now with no luck.

I've got a 2012 Retina MacBook Pro (so no USB-C ports) and have tried connecting using four cables including a brand new USB-C to USB 3.0 (SS) cable. I'm running iTunes 12.8.0.150 and MacOS High Sierra 10.13.6. I can't update to MacOS Mojave as some of my third party software will stop working but Apple states anything from iTunes 12.8 and MacOS 10.11.6 is supported so that shouldn't be a problem. I've tried both my MacBook Pro's USB ports (which are both USB 3.0 compliant) and have tested that they both work with all my USB 3.0 devices.

I feel like I've tried almost everything logical and am starting to clutch at straws. The only thing I can think of doing at home is buying the Apple USB-C to USB 3.0 adaptor (Apple don't appear to sell a USB-C to USB 3.0 cable) and trying that with the USB-C to USB-C cable that Apple supplied with the new iPad Pro. I also thought about buying yet another USB-C to USB-3.0 cable to try too, but my current cables are new (recent designs) SS USB 3.0 compatible and have all the pins in place (unlike the Apple supplied USB-C cable which is missing a number of pins) so I'd be surprised if that fixed the issue.

I would be real grateful to know if anyone else has experienced this or can think of anything I may have missed?