As a long time user of the original Last.FM Scrobbler for Xperia I was a bit sad to find out I couldn't install it on my Xperia Z1, so I decided to get to work myself. After taking a peek at how the original app did things I created my own updated variant! It's been simplified since I didn't think Simple Last.fm Scrobbler and ScrobbleDroid are all that important. The way the official app does scrobbling is pretty nice so I always stick with that!
Install through Play Store
It's pretty simple. Install it, run it once, enjoy music! After that the official Last.fm app will be picking up scrobbles from the Walkman app perfectly!
PS - I've tested it on my Xperia Z1 but don't have a Z Ultra. I don't know if it's necessary on the Z Ultra but would appreciate any feedback. Anyone wants to give it a go?
All code is open source and hosted on GitHub. Feel free to make any suggestions, I'd love to hear more!