Venue 11 onscreen keyboard not appearing on logon screen when devise is docked

When you tap the password box if the device is undocked it launches the onscreen keyboard.  If you dock the device it no longer launches it is the same in the search box on the metro screen.

If the device is connected to the folio keyboard the onscreen keyboard still pops up when you tap the password box

This is not the same as the bios keyboard that launches if the device is encrypted (that problem was fixed with the A11 bios)

On a couple of devices the keyboard appears the first couple of times but then ceases to.    On one device it randomly started working again for a couple of times then stopped.

I have tried with the OEM software pre-installed by dell with the A06 bios, A11 and A12 bios, and with a build image from a wds server using Microsoft select version of Windows 8.1

I have 2 batches of the devise have tested 9 from the first batch purchased in Dec 2013 and one from a batch received a couple of weeks ago.

The problem occurs on both A00 dock and A01 dock.

When I got the first batch there were drives available for Windows 8 so at the time I created a Windows 8 image the keyboard on this image works on the logon screen and the metro screen on any Dock.

I have a support call with Dell who have even tried replacing a mother board on one of the first batch but so far no clues as to how to fix the issue.

Has anyone else experienced this or found a solution?