I am trying this for "Track Purchase Order" scenario.
As of now this is the finding for "Track PO":
Works for - IE and Chrome on desktop (Windows 7 and Windows 8), Chrome on Android phone, Chrome on Mac OS
Doesn't work for - Safari on Mac OS, Safari on iPad and Chrome on Pad.
I can see that the request is initiated from the iPad but subsequently nothing happens and get the following error on iPad
"Service SRA020_PO_TRACKING_SRV failed.... Cannot call service with URL: /sap/opu/odata/sap/SRA020_PO_TRACKING_SRV;mo/"