I lost count of how many times it crashed in an irrevocable way forcing me to create a new AppVM. In the last crash the desktop logged out all of a sudden, the log in screen appeared, then all the windows were in the 1st desktop, while the LibreOffice document was gone, and any new AppVM failed to start until a restart.
I used LibreOffice in both Debian-based and Fedora-based Qubes. I haven’t faced such problems. I find LibreOffice stable. If you share more information on Qubes OS version, templates used, software installed (LibreOffice add-ons?), more context, more help could be provided.