Mobile.verifyElementExist(testobject, 10) waited for 90 seconds — far longer than the specified timeout of 10secs. Why?

You reported 90secs wait after a failture at Mobile.verifyElementExist(x, 10), but I am not convinced that you are reporting a fact. There could be some other cause of failure and probably you missed it. Please check the execution log again.

Or follow the guideline: