Wait for exists step is failing with the error below, when Test Studio is not able to find the element:

Object reference not set to an instance of an object.
InnerException:
System.NullReferenceException: Object reference not set to an instance of an object.

As a result the conditional steps are not working as expected and the test fails.

The workaround for this issue is to change the WaitForExists step to VerifyExists step and the test works.