Screen does not rotate upside down

Hello,

 

on my ET1 and MC40 I found:

 

Since I updated to Jelly Bean the screen does never rotate upside down.

Rotate to left and right is possibile.

 

This applies to all applications, even the systems apps like 'File Browser' for example.

 

Please help, I need this for customers who scan barcodes from a table holding the device upside down.

 

Thank you!