Tabs have to be 8.5*11, Tab shift is required to shift an 8.5*11 LEF document to print onto the .5 inch tab. If you shift it and it doesn't print at all, it missed the tab or tried to print on the opposite side (rotate 180 degrees)
As for 9*11, that is just done as heavy weight stock, if the document you print is 9*11 it is just a straight print job, if it is Letter size you will need to shift it manually.
If you print 5 bank tabs and only tab 3 prints, you need to print them in reverse order.
I can't get the numbers to print on the tab. I have xerox 9x11 tabs (3r4417). If I set 9x11 in mixed media with media stock tab add gets grayed out. if I set it to 8.5x11 tab stock it will print but not on the tab area I have moved tab shift as well as made sure my drivers were updated.