We have recently had a dramatic change in the behaviour of iOS devices accessing SSA. ?On loading SSA end users could pinch/pull zoom usually just one time before no more zoom requests were accepted.
Panning ceases to work though tapping a location will still successfully query features at that point and load the Information Panel, though after a few taps this becomes increasingly unlikely to cooperate.
The layers panel can still be selected, different Map Configs selected and layers changed. Addresses / coordinates can still be searched / manually entered and take you to the requested location, though panning and zooming is still unavailable.
SSA current version is 12.0.0 (rev. 42242)
PC access remains unaffected, iOS devices running 11.0.2 or earlier are also unaffected.
We tested a neighbouring council's publicly available SSA (12.0.S01 rev. 42418) and it remained fully functional on iOS 11.0.3 devices.
Currently we are updating our Test server and if that resolves the issue we'll migrate the updates to our Production environment.
Interested to hear if others have come across this, also serves as a bit of a reminder to keep up with patches as released.