Please note I performed a new installation just in case of and the problem persists.
Ok I found a workaround.
Instead of cliking on the 'import' button,, navigate within the existing list of folders and click on the '+' button. Then select your new folder and Lightroom will work correcty..
Apparently the issue may be situated when clicking on the 'import' button and when browsing into the list of drives. I have a network drive and as this one was shut down at time of bug reporting this may cause the issue. I will continue further with the investigation.