Vncviewer session freezes after session lock

I have F39 on both sides with tigervnc-server running on one machine, and I start it for a particular user, and works fine. I can login fine and use gnome-session. Yet if I let session lock screen, then I can’t get back to session. When entering password for the user if (wrong) it says wrong password, if password is OK, it stays in this screen, and doesn’t unlock it. I’ve tried to kill this vncserver for this user and restarted, so it offers me again to enter password and it freezes again.
What could be wrong? What I should be looking at? Normally I use sessions for shorter time, and when I finish i stop vncserver, so this doesn’t happen, and on other locations I use xfc sesssion and there it works fine even after screen lock.