Scroll pane component + tab index

I am having trouble with setting the tab index for textboxes within a movieclip (library attached) inside the scroll pane component.

my scope is this:
clip.scrollPane.content.textBox_0.tabIndex = 1;

I am able to set the stage.focus to the textbox, I am also able to set the tabIndex to the textbox, but each time I hit tab the focus is then moved to the scrollPane clip itself.

If I set the tabIndex of the scrollPane clip to 99 it still receives the focus on the first tab hit.

If I set scrollPane.tabEnabled to false, it shuts down tabbing within the clip, children included.

setting the tabChildren to true doesn’t change the results, on the first tab hit, my scrollPane clip receives the focus.