Mobile devices not stating tests

My mobile tests are failing with :

error: UnknownError: There was an error. Please try again.
at
...
at
==== async task ====
WebDriver.createSession()
at
...
at
error: UnknownError: There was an error. Please try again.
at
...
at
==== async task ====
WebDriver.createSession()
...

Desktop browsers have no issues. My tests are running through a queue via node Async queue -> Async each

The configuration capabilities seem to be fine;

CAPABILITIES-> { browserName: 'iPad',
platform: 'MAC',
browser: 'null',
browser_version: 'null',
os_version: '7.0',
resolution: 'null',
'browserstack.bfcache': 0,
build: 'Untitled Build',
project: 'JJ Foodservice Order Pad',
'browserstack.user': 'xxxxxxxxx',
'browserstack.key': 'xxxxxxxxx',
'browserstack.debug': 'true',
acceptSslCerts: 'true',
os: 'ios',
device: 'iPad 4th Gen' }

again desktop browsers run fine but mobile tests across all browsers fail with a timeout. Any ideas

Many thanks