I am running vncserver on OPENSuse Leap 15.1 like so:
myusername@opensuse:~> vncserver

You will require a password to access your desktops.

Would you like to enter a view-only password (y/n)? n

New 'video:1 (myusername)' desktop is video:1

Creating default startup script /home/myusername/.vnc/xstartup
Creating default config /home/myusername/.vnc/config
Starting applications specified in /home/myusername/.vnc/xstartup
Log file is /home/myusername/.vnc/video:1.log

When I connect from Windows 7 using either TightVNC Viewer or UltraVNC Viewer I am presented with the linux login screen as expected.
But when I try to type the password the characters appear to get deleted so I can never enter the password fully.

I can only type about 2-3 charachters and then they get deleted. Its as if there is a refresh every few seconds that clears what I have typed.

What is this happening and how can I resolve it?