No. As they are stored in all of your Sonos players, this is unlikely. Maybe you just have a bad network connection, have you tried (temporarily) hard-wiring a speaker to your router?

If you get them back, you can back them up using my iOS app (see profile).

...and restore/transfer them to a HH ?

Restoration would require a UPnP app, such as UPnP Spy, or a custom app I could sling together for a customer who needed it.

Ah I wasn’t sure @controlav. It would be nice to have an ‘all in one’ App that catered for both the export and import of the .xml files and to keep things simple and available in the one App.  

True, but I have always been wary of non-recoverable “write-operations” to the Sonos system, and this falls into that category. I’ll take a look for the next update, the code is simple, but the testing is not, and the UX always takes me too long.