Q:  Our customer has reported a problem with XONE:4D hanging up sometimes and displaying a ' 5Ft' code on the LCD.

A: This shows the mixer is in SHIFT mode

(see p.39 of the XONE:4D User Guide for details).

The mixer only enters this state when the SHIFT / POWER ON SETUP encoder (C0), located above the Left-hand jog wheel, is pressed and held for approximately one second.

It's probable, in this case, that the encoder has, accidentally, been held down too long.  This is more likely than the mixer switching layers by itself.

When in Shift Mode, the mixer may appear to stop controlling functions in Traktor; this is likely to be because, when in SHIFT mode,
MIDI signals are transmitted on a different MIDI channel than in un-shifted mode and the A&H pre-configured .tsi templates do not include assignments for SHIFT layer controls. 

Unless Traktor functions have been manually assigned to 'SHIFT' layer controls, control of Traktor will not be possible until the mixer is to return to its un-shifted layer.
To do this the SHIFT/POWER ON SETUP encoder should be pressed and held, again, for approximately one second.

The XONE4D's BPM display will only display SFT when the SHIFT layer is enabled

We hope this helps, but if it doesn't provide a solution to your problem and you cannot find the answer within the XONE:4D, TRAKTOR PRO User Guides,
or in product information available on the Allen & Heath, or Xone Series websites, please contact your local A&H distributor for technical support