Hi,
Just so you are aware the proxy sensors are only used to action the steering direction change and are not used once the steering direction change has completed (the 45 degree one is used for carousel but that is seperate). Most likley a passing seal on the rear cylinder. The UK services team can be emailed uk.services..combilift.com, just replace the 2 dots in the middle with the at sign and they will be able to help you. Combilift also has lots of technical information on the web site and knowledgebase that is available to dealers.

Possibility of a rear steer cylinder bypassing internally past the piston. Or by passing in the 6 port steering change over valve (valve locks fluid flow to rear steer when in side mode). But since its intermittent I would recommend looking into and installing the rear steer cylinder check valve kit (CPHY0455) if you have a rear steer cylinder p# CMR00024 as this kit was made to prevent rear steer cylinder from creeping.

By passing while sitting still or moving?

What fixed your problem i am having the same issue?

the solenoid that controls your rear tire hydraulic is likely bad

Rear Wheel locks into place- then sometimes immediately, sometimes after a while drifts out of alignment. Checked proximity sensor, no dirt or debris and connection good. Only does it now and again, working perfect right now but I am hoping to find out what it is before it becomes a major problem.

Which wheel is creeping all or just one and is it creeping while using it or when its sat not being used?