Upgrade from KIS to Standard login fails

[Wallaby53]

I have a 5 PC License for KIS. All PC/Licenses are working fine.

After upgrading one of the PC's from KIS to new Kaspersky Standard I am running into Account login problems. Though I can sucessfully login on the same PC via Firefox to the MyKaspersky account... the new installed Kaspersky Standard is failing to login into the valid MyKaspersky account.

Error ist "You entered an invalid password" though I am logged in to MyKaspersky via Firefox and I am using same PW to login via newly installed Kaspersky Standard app as I use for Firefox to login to MyKaspersky.

What am I doing wrong? Where is the problem? Why is login via app failing? Can be me, but how can I fix it?

Stuck in the middle...

Thanks for feedback.