Hi SaiKishor-MSFT thanks very much for the followback.
Please check attachments for version.
The problem was the pop up to select the files to upload has hidden behind the "Upload files table" so i was unable to select. I just checked and it seems the issue disappeared. I did. not to any update. It still would be good to know what happened and how can I fix it next time in case it happens when I critically need to upload files.