Mine was the same,various intermittent problems for a while, that I didnt realise was only happening
after rain or washing.
When I took into the dealers it was working ok, but as soon as I mention the symptoms they asked was it playing up after raining or washing, so they already new of this issue with the Z and promptly booked it in to have the switch replaced.
To be honest I wanted it done urgently because on one previous occasion the boot popped open whilst driving along the M4 at high speed, this was on a clear dry day, but 2 or 3 days after I had washed the car .
I was also locked out from the car on a few occasions, locked inside on one occasion, luckily this happened on my drive so I climbed out through the window.
Even the parking sensors and parking screen display were affected, if I put the car into reverse it sometime showed a warning on the front of the car, or would just throw out a warning when driving along. :crazy:
Anyway hope you get yours sorted soon. :thumbup: