Join Date: Oct 2018
Location: Newcastle upon Tyne, UK.
I had this exact issue with my new (to me) 2018 ATAS after only a couple of (wet) days of getting it - it started but stopped when I let go of the switch unless I increased the revs for a minute or two. First it was once in a few times but seemed to get worse until it was every time.
I bought the bike from a dealer some distance away and was not keen on going straight to the local dealer as I've learnt in the past that they use the "let's keep changing things until we strike lucky" method of diagnostics.
After reading lots of threads on here and other forums I stripped the switch housing apart, cleaned the contacts with contact cleaner, tweaked them slightly with a jewellers screwdriver to ensure they made good contact and gave them a light coating of ACF50 to try and prevent the issue returning.
Started first time afterwards and has done so every time since - probably over 50 times so far.