As @nontrivial did, after reinstalling Ubuntu Touch in devel version, I got :

start: unknown job: anbox-session

I think I got that because I ran "anbox-tool install" as root whereas it is not asked. I was able to correct this with :

sudo chown -R phablet: anbox-data/
anbox-tool upgrade

Now anbox works fine and I was able to install an APK.

Hello,

I had the same problem with my Nexus 5 today when I tried to install Anbox.

First, adb is not working with my Nexus 5 on Ubuntu Touch, so I used the terminal to reboot in bootloader, then I was able to flash the boot-img with fastboot.
Since this moment, the Wifi controller was not detected :

ifconfig wlan0
wlan0: error fetching interface information: Device not found

Since the boot image for Anbox broke the Wifi, and no simple mean exists to repair it, I tried to put back the original boot image with Wifi working : I can't understand why it doesn't solve the problem at all.
I am reinstalling Ubuntu Touch in devel version, I'll let you know if it corrects the problem.

I think the doc page (https://docs.ubports.com/fr/latest/userguide/dailyuse/anbox.html) should not consider that Anbox supports the Nexus 5 and the buggy boot image (http://cdimage.ubports.com/anbox-images/anbox-boot-hammerhead.img) should be urgently removed to save hours of labor to people that finally get a completely useless phone...

As proposed by @nontrivial on July, I can help to correct the doc. What should I do for that ? Send a corrected version of the HTML file on the forum or to a particular person ? Don't hesitate to tell how we can help.

Thanks,