Rear Wash/wipe
 

Hi I'm new to this forum and would like some advice on my 2018 Discovery HSE Luxury.
My rear jet wash does not spray immediately when the button is pressed and I'm sure it is supposed to. It will spray eventually if the button is pressed continuously but I don't believe that this is correct. When the car was last serviced at the main dealers I asked them to check it and the mechanic said that it was working correctly. I am not convinced as if the button is pressed momentarily the jet motor runs the rear wiper wipes once and then after the first wipe the motor runs again for a second spray but no water is sprayed out.
I assume there must be some sort of non-return valve somewhere that keeps washer fluid in the pipeline.
Thank you all for any advice most appreciated.

Mine take a little time to spray also. Always has.
In order to wash the rear camera, you need to be in reverse gear I believe.