Focus/Blur and Voice Over Commands

Dear WAI,
I work with a team on making interactive science simulation accessible (PhET Interactive Simulations).

In recent Quality Assurance testing of a prototype for the Resistance in Wire <https://phet-dev.colorado.edu/html/resistance-in-a-wire/1.5.0-rc.5/phet/resistance-in-a-wire_all_phet.html> simulation, we found an issue when using Voice Over. It seems that Voice Over does not successfully blur (i.e., remove focus) from a slider control that has focus when the user uses the native Voice Over command, command-option-shift-up arrow, to exit web content.

The result is that the slider remains visually focused and operational via all the normal keyboard methods, even though the user is technically “out of web content”. In this case, Voice Over will not announce slider values if the user adjusts the slider. In this case, Voice Over only announces aria-live alerts. This means that the user is not getting all the information they are supposed to be getting when they adjust a slider. In addition, if the user re-enters web content using command-option-shift-down arrow, their virtual focus starts at the top of the sim with the H1 content.

We think the lack of blurring is a Voice Over bug.

My questions to the group are:
Are we supposed to do anything special to make Voice Over blur focus in the case, or is this indeed a Voice Over bug?
Where is virtual focus supposed to go after a properly blurred event? 
Is starting at the top of the page the correct place for the virtual cursor to be after a successful blur event, after successfully exiting web content with the native Voice Over command? 
Starting at the top, seems to be the default behavior. Is it the correct behavior?
We have done a lot of user testing with blind users. Exiting web content after focusing a control is not something that has occurred during usability testing with Voice Over users. 

It would be great to get some thoughts from experts on this list regarding this blurring issue.

Sincerely,
Taliesin Smith 
My work email is Taliesin.Smith@colorado.edu <mailto:Taliesin.Smith@colorado.edu> if you would like to know more about our work on making interactive science simulations accessible.