Adding the firewall rules to allow communication to/from 10.0.75.0 wasn’t doing anything - it only worked for me when I disabled it completely.
I kept thinking a bit more about this issue. And in my case, it comes down to the way the virtual adapter was being profiled by Windows (i.e Unidentified Network) - and by default windows treats Unidentified Networks as a ‘public’ network, for security reasons.
So I went to Local Security Policy > Network List Manager Policies and Double-clicked ‘unidentified Networks’ and change the location type to ‘private’. Then I restarted Docker and it worked.
I couldn’t find another way to profile the virtual adapter used by Hyper-V/docker. Another possible solution would be to turn off file/printer sharing on Guest/public networks.
Might be useful to someone else.