Getting CardDAV to work on Mobile
This appears to be the case on at least two servers, and I'm pretty sure why it's causing an issue on mobile.
When the address book is pulled up on desktop, the middle of the screen is blank and you must click an option ('Default Address Book") on the left to bring it up in the center. On mobile, this sidebar with options is unseen, therefore you are unable to view the address book. Tilting to landscape does not solve.
Nomad for Android