Confluence server (6.1.5.6) is not currently fully usable via our company iPhone's ("8"). Any ideas?

[Hugh Bathurst]

"Confluence server (6.1.5.6) is not currently fully usable via our company iPhone's ("8"). Any ideas?"

* Confluence (6.15.6 on our company server) search window not opening at all on company iPhones.  // We WERE able to use searching from company mobile phones fine prior to 10 Jul 2019 upgrade from Confluence 6.9.3~ to 6.15.6. Only noticed 25 Jul 2019 (recently). (Copy of "Summary" at Unsolved Mysteries BoK.)

[Hugh Bathurst]

We're currently stuck on this unsolved Confluence mystery so any ideas welcome .. Thankfully our users have not yet demanded Confluence (searching) access on mobiles be made usable (yet). 

* We've recently gone to Office 365, which is better than our IBM Notes world, and I don't know the full technical story, but I understand we're using the updated version of mobile iron on our Company iPHone 8's to access our Confluence 6.15.6 instance which is on our server.

 Not sure if related but we're seeing "you're URL doesn't match" messages on iPhones when we first access our Confluence instance on company iPhone's. 

Happy to provide more facts if helps solve this current challenge.