You could try Signing Out then Sign Back in. You might need to re-enter the serial number and if it is an upgrade serial number the serial number from a previous version.
If that doesn't work uninstall and reinstall and use the Adobe CC cleaner app to make sure all parts of LR are removed.
Thanks for that.
It was a new install so there is no previous version.
It's a lot of work to uninstall and reinstall. I have only wireless wifi so takes forever to downlaod. As I only installed late last year I'll ignore the update for the time being.
Thank you very much for your answer.
If you have a way to get to a different computer with faster internet and you have a flash drive that you can used to transfer the download to your existing computer, then you can download a standalone installer along with the latest patch to 6.4 when you're at the other computer and then use what you've downloaded to do the uninstall and reinstall. Or just leave your current computer on and plugged in and disable auto-sleep and let the download run over night.
The installer and patches are available, here:
Thanks for that info and suggestion.
I'll give it a try. In the meantime it appears that some updating has happened as when I went to import new images into LR - there was a different screen.