Cannot type password when using vncserver

[LEFT]I am running vncserver on OPENSuse Leap 15.1 like so:

myusername@opensuse:~> vncserver

You will require a password to access your desktops.

Password:mypassword
Verify:
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?
[/LEFT]

I got around this by using the command line entry with the password on the command line:
Windows:

"C:\Program Files\VNC\Ultraviewer.exe" /autoscaling /password mypasswd 192.168.1.119

Linux:

wine "C:\Program Files\VNC\Ultraviewer.exe" /autoscaling /password mypasswd 192.168.1.119

This enters the password for me. My Ultraviewer is version 1.0.9.5 - Other version might work - this one works fine for Linux and Windows clients.
I found the windows version works better than the linux versions. I use the default wine from OpenSUSE repos.