When launching my debug build of master with option --nodefault, no UI appears. If not launched with --nologo, the splash screen appears and disappears, but no LibreOffice window. Running it under strace, the last line is: futex(0x116f094, FUTEX_WAIT_BITSET_PRIVATE|FUTEX_CLOCK_REALTIME, 7, {1322500654, 573238000}, ffffffff
Possibly not crashed, but just does not show any UI. It seems this might have been on purpose and a "good thing". Anyway, the discussion happens in bug 42470 *** This bug has been marked as a duplicate of bug 42470 ***