Bookmark says file does not exist

I have bookmarked a few files and 99% of the time I can open them via the bookmarks. But every once in a while some files will suddenly start to fail to open and I get the error that the file does not exist. But the file does exist and it has not moved. I have only noticed this when trying to open Xls files, but I am not sure if this is the only file type that gets “lost”. If I then open the Edit Bookmarks window, then I can copy the full file name from the dialog box, pop it into my File Explorer and open the file with no problem. So then I bookmark the same file a second time and all is OK for a week or two or three, until suddenly I start to get the same error again.
Has anyone ever had this experience and is there a solution?
I use Windows 10 full updated and the latest version of LibreOffice. I have been having this problem for at least several months.
I hope someone has a suggestion how to permanently fix this since it is SO annoying.
Thank you.

I have bookmarked a few files

How? Bookmark is a terminus from Writer and isn’t a reference to files at all. Are you in fact talking about Sheet -> Link to External Data and Edit -> Links to External Files? Or are you talking about Hyperlinks?