UCP - You are currently working in offline mode

I am listening to call recordings in UCP. Log on from chrome under windows and all works OK.
Log in from Firefox under windows - Works OK
Log on from IE and can’t playback, I get ‘You are currently working in offline mode.’ displayed.
Chrome from IPad also does the same as does Safari on Ipad

What is the diference? Whys does UCP only work from some browsers?

FreePBX 13.0.70

“Offline mode” typically means an ajax call failed. I don’t know if any of the dev tools are availible on the ipad but you would want to look in the javascript console.