• The troubleshooting steps undertaken so far:
• Reset NVRAM and SMC controller
• Booted in SAFE Mode
• Created a new user on my MacBook Pro
• Installed a fresh partition and install of macOS Catalina 10.15
• Reinstalled mobile device firmware package on my MacBook
• Reset all iPhone settings (but not wiped it and reset to factory settings)
• Deleted non-Apple launchdaemons on my Mac
• Disabled anti-virus software (Intego's VirusBarrier) and VPNs on my Mac
• Deleted the Mac's plist in the lockdown folder associated with my iPhone. This plist is used to check that the Mac and my iPhone have trusted each other previously 
• Reset privacy settings on my iPhone. Resetting privacy settings, similarly deletes the trust file on the iPhone which is used to check you have trusted the Mac, similar to the lockdown plist on the Mac
• Triaged and booted my MacBook Pro into macOS High Sierra 10.13 at the Apple Genius Bar
• Replaced the MacBook Pro's logic board and I/O board
• Tried multiple iPhone XS at the Apple Genius Bar, and all exhibiting the same issue with their own Apple USB to Lighting Cables