Saved Math Formulas got corrupted on Mac

I am using OS X, Version 10.8.5. I wrote the first page or two of an article using Math Formula in Libre Office. I opened, edited, saved, opened, edited, saved, etc. over a few days. The result looked very nice, especially the PDF image. Then I set it aside for a month. When I opened it again all of the displayed formulas except the first two were drastically shrunken. So were some of the in-line formulas. Some were out of sequence. The first displayed formula is still correct. The second has been replaced buy a hugely enlarged version of one of the in-line formulas.

What could have gone wrong?