Strange behaviour from IOS App

When I use a dimmer in the main website the value is kept and is reflected in the IOS App. When I make a change to the dimmer from the app I can see the change occur on the main openHAB page and is reflected in the log file but after releasing the dimmer the value goes back to whatever it was before(usually zero). It is as if the IOS change is overwritten by some other stored (default?) value.

Have I omitted some config steps ? I can see my site fine, the date/time updates, as does the weather and astro information. I’m letting the app discover the openHAB instance locally. Additionally, I’m not using my.openhab and have no desire to do so at the moment.
I’ve seen similar issues with the dimmer springing back but these don’t seem to relate to the app only and were - as far as I can see - fixed.

I’m running 1.8.1 on a raspberry pi 2 if that’s of any use.

Many Thanks