I opened a thread similar to this Issue with deploying Tableau Mobile through Maas360 where we wanted to hide 'RemoveTableauOnlineButton' and 'HideServerNameField', we found no answer.
For us it is boolean values that weren't been able to pass correctly, string attributes were working as expected.
I also reached out to Tableau support at that time but they weren't helpful.
Try calling them again to see if they have a solution.
Both fields you want to use is working in MobileIron.
Maybe you can try using the plist mentioned above to try again.