Send Keys Tab working on browser itself and not the applcation page

This is related to another issue that I have with selecting a list item - clicking on it does not do the same thing as a physical mouse click or selecting or any other click options - nothing works - so now I want to Tab down arrow enter etc with send keys as my last resort to get this item selected and and and for the page to load upon selection.

However when I use Send Keys tab its working on the browser itself instead on in the browser window in the application where I’m expecting the send keys tab to work from the last element interaction.

am I doing something wrong because i cannot get send keys tab to work in the web app - seems to just want to tab around the browser. do I have to do something special to make it work on the app and not the browser itself?

here is a link to a video that might explain better