Hi @barbroos,
On my installation, the “Import Wordfence Options” button is lighter until the alphanumeric token given when you performed the export is pasted into the text box: https://www.wordfence.com/help/tools/import-export/
If the button refuses to enable at any time, it’s likely to be a JavaScript conflict. You can normally test this by temporarily disabling any custom themes and plugins (apart from Wordfence) and see if the button enables when it’s supposed to. If so, import your settings first, but reenable your plugins one-by-one and check back to the page each time to see when it behaves incorrectly again to find the cause.
Thanks,
Peter.