As previously you were able to edit/select these fields and not now, seems there are some permissions for editing these field and you may not have that permission (or might have been removed recently from your profile). There is also a chance of removing these fields from HeaderDetailsEditable group and causing the issue.
Please check first is there any permission associated for these fields to be editable and whether you have the same or not. Also you can check the configuration/customization and associated groups for these fields to get more insights.
Hope that helps!
Thanks, we found out. one of the groups have been removed from my user id.