Find and Replace (with regular expression option) freezes when globally replace end of paragraph ($) with another character (##) in this case. When I try to replace the paragraph mark ($) with ## globally, LibreOffice freezes. I can not save, close the Find and Replace Dialog or even exit. I had to use Task Scheduler to terminate LibreOffice. This is on Window 7, LibreOffice 7.0.4.2 (32 bit version).
*** This bug has been marked as a duplicate of bug 139483 ***