Doesn't GRiSO like rain?

Yesterday morning I had pleasure first time ride in (light) rain. In work I parked GRiSO under the roof. In evening (after 12 hours of drying) I started, gear 1 left clutch and nothing - no movement. So I tried to shift to second gear and engine died. I found out, there is missing / broken contact on clutch as I was not able to start again and gear box do not cooperate to find neutral.
So I press and release clutch and tryied to move bike and engine block movement after about half meter. Repeat about 3 times, then gear to expected position of first gear and repeat the same. Then suddenly movement was not possible after releasing of clutch and I was able to find neutral again. I started and drive 30 km to home without any further problems.
Do you have idea, what has happened and how to prevent it in future? All oils has been changed at spring and GRiSO (should) have 22000 km driven.
Am I able to repare / install sensor in clutch?

You may have a faulty side stand switch the engine won't run in gear if the stand switch is indicating "Deployed", this used to be a very common fault on earlier Guzzis.

Thank for suggestion, but stand switch should be OK, as engine did not died when I geared to first step (neutral light has turned off) and do not describe problem with clutch / gear box.
I think it should be something else.

I mentioned the side stand because I believe it's the same switch they used on earlier models. Most bikes have had it disconnected because of a similar fault, engine dying in gear.
If it happens again exercise the stand a few times it may get a better contact proving it's the switch.

While the neutral indicator light may go out it does not necessarily mean that the bike is in gear. If the engagement dogs aren't lined up correctly it can't select a gear. If it does this again try keeping a light pressure on the gear lever and slowly releasing the clutch. At some point you will feel the lever drop as the dogs engage and you can pull the clutch in again and be ready to move.

Likewise if the neutral switch is a bit dodgy or has a bad connection the light may not illuminate when neutral is selected and this will prevent the bike from starting. If the clutch switch is also unreliable the two combined may make for a 'No Start' situation even is the clutch is fully engaged.

Pete, I resolved problem as you mentioned, with light pressure.
What I do not understand is why I was not able to return to situation with neutral indicator on.
And why (at engine down with gear in) after pressing and releasing clutch I was able to move GRiSO about half meter until engine prevent further movement? This I repeated more times, until engine block movement immediately. At than moment I was able to select neutral again (indicator on) and whole bike works as usually. Is there any spring inside clutch, what can get to "bad" conditions due to rain? I am asking because till now it never happened and only different condition was the rain.

No, no. It's nothing like that. Give me a day or so and I'll try and explain but I think the problem is you don't understand how a 'Constant Mesh' gearbox works.

Pete, do not spend additional time with it. So everything is as it should be and I will find some information about constant mesh gearbox.