FortiClient SSL VPN Problem

Greetings!  Can anyone help me with this issue..

I have in my company an FortiWifi 30D.

We are working with FortiClient SSL VPN about a year with no problems.

2 months ago we had some problems in a few machines but it was the service that wont start automatic. We needed to start manualy or configure to start automatic with system in services.msc and it solved.

Now, since last week, some machines with windows 10, after windows update, when we open the browser and made login the Connect button(Tunnel mode ribbon) it's grey..we can't press it...

I check the service and it's running... how can i solve this?

Thanks for your time and help

Best Regards,