I asked about this when it happened before. Nobody had an answer.
I saved a document with formulas. I continued to edit and tried to do another save. A box appeared telling me “another user” had modified my document. There is no other user unless there is very strange malware in my Mac that does nothing I have seen but corrupt formulas in Libre Office documents. Formulas are moved from place to place, inserted in strange places, enlarged, and shrunk. Using a Mac with OS10.11
If I were allowed to attach PDFs, I could show you.