Disappearing footnotes

I have a problem with disappearing footnotes. All that remains is the number but no footnote is attached and the number is no longer linked to a footnote.
For example,
In 1872, Ghen and son-in-law Edward T. Starr gained approval to construct a wharf in the harbor.665

I thought Zotero might be causing the problem, but even when I typed inserted and typed in one of the footnotes from within LibreOffice (without using Zotero) it also disappeared. The document is large, 111 mb, about 320 pages with photos.

(I should say that very early on, I didn’t realize that Zotero underlined footnotes and I eliminated the underline by hand, but over time perhaps 100 footnotes have disappeared. I go back to older versions to retrieve the footnote and copy and paste it back into the working document.

I have heard LibreOffice does not respond well to Copy and Paste of footnotes.) The doc has over 1200 footnotes. I have turned off auto update of the bibliography.

Thank you all!!

I’m using LibreOffice
Build ID: 60da17e045e08f1793c57c00ba83cdfce946d0aa
CPU threads: 4; OS: Mac OS X 10.13.6; UI render: default; VCL: osx;
Locale: en-US (en_US.UTF-8); UI-Language: en-US
Calc: threaded

First steps

Specifically try steps 1 and 2

Thank you. Will do. OK, I installed the newest version of LibreOffice, BUT the java runtime environment is incompatible with Zotero. My older version of LibreOffice opens the file but no longer can access Zotero even though I have reinstalled the extensions from Zotero. It looks like a need to downgrade to Libre Office 6.4.6 or 6.5 max. Are those available? I don’t see a choice to download them. Thanks again.

Have a look in the archive
Index of /libreoffice/old

See also:
I cannot re-install the LibreOffice - #7 by Hrbrgr

Thanks, I did try the archive but the older versions are not set up to automatically install. I wasn’t technically adept enough to figure out how to do the install.

However, somehow, I was able to get LibreOffice Version: working with Zotero again. (I tried switching the Java runtime in the Advance menu among other attempts. Not sure what finally did it, but Zotero extensions are once again working).

I’ll see if Step 2 you suggested will solve the disappearing footnote problem.