Missing spaces when converting to Word

I’ve done some searches in the forums trying to see if this has come up and couldn’t find anything.

When I convert my Scrivener files to Word, sometimes random spaces between words go missing. They are NOT missing in my original file, but when I send them to my critique partners, they come back with corrections to add the missing spaces.

My publisher encountered major space-deletion problems with my last book and it seemed to be an RTF issue. When I resaved the file as a .docx, it appeared to solve the problem. But it has continued to happen since then with other files.

Anyone encounter this and maybe have a solution? Thanks!