Difference between icon behaviour Web/Android v iOS

Been trying to develop a simple device to give me a read-only binary status output panel - i.e. no switch or slider for the user, just an animated icon. I started with the the BinaryLight1 files and renamed the device service etc to my own. First I chopped out the action code so that the slider did not call the switchpower service (the slider spins the whirly thing for a few seconds but does nothing). So far so good. I then chopped out the code for the switch/slider. At this point the web and Android worked as intended - animated icon only but the iOS app stopped animating the icon.

After a bit of switching code back and forward I noticed that the icon behaviour in iOS is different. In the web/android app, for example the z-wave signals coming from the top of the socket symbol change from grey to green as the png files would suggest. However on iOS, the whole icon turns green (also the green socket icon is one pixel out so it hops left and right!). This suggests that iOS is using different icons but I could not see an all green icon in the icons folder. Does it just change the colour on the fly?

When I added the code for the slider back in on iOS the icon started to reanimate again so the icon behaviour seems to be tied to the presence of the slider rather than separate on the other systems.

Is there any way to fix this?

Richard