Installed Libreoffice from terminal command "sudo apt install libreoffice"
Open libreoffice from menu and the application opens like this as expected
If I create a writer or calc document from the menu a blank writer or calc document opens and the system immediately locks up.
Just booted into my hirsute installation to check your observation (and to update everything).
I did not have to install LibreOffice as it was included in my install. All LibreOffice functions seem to be as expected, my system does not lock up or otherwise malfunction.
I concur with @mdooley. Checked by opening blank documents/spreadsheets and also my (existing) files. No freezes. And my PC is not exactly powerful. It's Celeron N3060, with 4Gig of RAM.
Why you had to install libreoffice from command line? It is part of default install.
Edit: What version is your libreoffice? Mine is 7.1.1~rc2-2ubuntu1
I selected minimal install during setup so LibreOffice was not installed initially.
I then installed synaptic and installed a lot of other software before even trying LibreOffice. (Chinese mandarin language and pinyin keyboard input) Bu hao!
I have just completed a fresh install with the "normal" install and LibreOffice opens. I havent't installed anything else yet and so far Libreoffice opens and runs without locking up.
OK. I'll try a minimal install from my side and see if it makes any difference.
Well having tried a fresh install (not minimal) Libreoffice worked for a short time until I tried Firefox and signed in and synced my bookmarks and extensions. After that Libreoffice document would freeze again and it would also freeze if I used the workspace switcher. Using Mate tweak in window manager section I selected Marco (No compositor) and had a slight improvement but still freezes at times.
I enabled the proposed updates from software manager and updated the system and it hasn't frozen so far.
I was about to ask you to try a fresh install (minimal or normal). I did minimal install and installed libreoffice. Played around with it and running file manager and firefox for sometime but it did not freeze.
I run hirsute on Intel PC with integrated graphics (marco with compositor) and also on virtual machines. Unable to reproduce.
Hello colinux
Perhaps "minimal install" plus LibreOffice as a Flatpak might work better for you? 
