In SharePoint 2013 online, i noticed inconsistent behavior of the folder option in views. We migrated some 2007 views also to SharePoint 2013 online. Not sure about the relation to it. Still, as you can see in the screen shots,
1) doesn't show the Folders option at all
2) Shows Folder Options but has only two radio buttons
3) Shows Folder Options but has additional options.
How to get a consistent behavior? Is there any settings or require some fix?
Depends how they were migrated but some libraries are probably using an old legacy library template. To change that you’ll have to migrate content instead of the entire list. The other option probabaly related to the manage content types option being turned on for the library. If not probabaly library template related as well. When you migrate it will move the library with same version template it’s using if supported.