and also let me correct you on how to troubleshoot this kind of errors.
Step 1. you know you have the activity that went haywired, no condition defined or not assigned to an instance of an object means your variables are null.
CHECK your variables or arguments output window at the faulted activity.
Step 2: think where you passed the specific arguments value from, in this case WIID originates from your process.xaml, here set a breakpoint on ur invoke navigate to widetails workflow (the activity where the error originated from). check your import arguments, check if its correct (u’ve done it). ok next run debugger here.
again, check your variables or arguments output window at the invoke activity breakpoint. what does that tell you? Null or not null? if null (or not null), then what can you infer? WIID does not originate from your process.xaml, then where can it come from? ask yourself these questions when u troubleshoot.
Step 3, you already know that when you set breakpoint on the first layer (the Main.xaml) your value is present.
combining the results and inference you get from step 2 and step 3, what can you tell?
its a good attempt at trying to troubleshoot from your previous problem. but you are kinda beating around the bush abit with ur troubleshooting method. always remember to use debugger with a mindset like this, Layer 3: navigate > invoke activity > Layer 2: Process.xaml > invoke activity > Layer 1: Main.xaml.
work your way up each layer, you will definitely find where the error exist.