In OOTB Work-.Open activity step 13 there is a pre condition check. It is checking the status is having Resolved or not through inString function which returns int. Though case is not resolved, still it becomes true. And setting Param.ReadOnly as -1. And thus making it Review Harness again.
Please help if I am missing something. Or this is an issue with the activity.
And what steps exactly to follow to open a case in perform mode.