The LR site states the following... In case it was missed (probably not, but trying to be helpful) :
TRAFFIC SIGN RECOGNITION LIMITATIONS:
The system may provide false information or function incorrectly in the following conditions:
The windshield area in front of the camera is covered by a sticker, misted over, dirty, covered in snow or mud, etc.
Traveling in adverse weather conditions. For example, heavy fog, rain, snow, etc.
Traveling in an area not covered by the navigation system.
Driving toward very bright lights.
Concealed or covered signage.
Non-conforming road signs.
Navigation information is incorrect.
Found at: http://www.ownerinfo.landrover.com/document/3A/2016/T23993/17969_en_GBR/proc/G1803649