Running Windows 10, Libre Office 18.104.22.168 X 64. Same issue with all modules - Exit Libre Office from File drop down does not work in any of the modules, at least most of the time, but clicking the X will.
Thanks for reporting. It was reported earlier in Bug 97761, so closing this bug as a duplicate.
*** This bug has been marked as a duplicate of bug 97761 ***
*** This bug has been marked as a duplicate of bug 92516 ***