Steps to reproduce:
Tools --> Options --> General --> use libreoffice dialogs, should be ticked
Open a new document. (I tried Calc and Writer)
File --> save as --> click the "new folder icon".
Expected behavior: the opportunity to create a new folder is provided
Actual behavior: save as dialog closes
Tested on Win7
*** This bug has been marked as a duplicate of bug 78845 ***
I did find a temporary work-around (until the bug gets fixed).
Options>Use OpenOffice Dialogue
change to uncheck Oo methods.
Now uses Windows(OS) methods instead.
Hope this helps -R