User Description:
Upon deleting a subfolder in the content browser, your currently open folder displays many objects from other folders as well.
Summary:
Deleting a folder will cause the content brower to show content not realted to the parent folder.
AnswereHub URL:
https://answers.unrealengine.com/questions/88120/deleting-a-subfolder-behaves-strangely.html
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-897 in the post.