Yes, I found the same problem but works fine.
Although you don't see the secrets, in my case, the clients can connect to VPN's without problems. Then, if i close Winbox, and then reopen, the secrets is here.
I detect the same problem with the ROUTES!!! this morning i don't saw the ip/routes, reebot device and, WOW, the ROUTES is here!
Maybe is only the viewer problem...
Carlos Martínez Ramiro