Tried to run the InvokeBackground in examples ... nothing. I did notice that the sample examples for firstnamelastname and getSimpleDetails required the addition of "label", to appear preoperly.
For example: Label 'FirstName' or Label "Age" in the second case and the example showed properly.
I cut and pasted the InvokeBackground.ps1. It runs but only shows the basic form. No TextBlocks ot ProgressBar. And no errors.