I also would like to add that I did change them to
/index.php/%postname%/
and everything seemed fine.
I went away for a couple of days, and when I checked my site, all pages were not opening.
So, I changed back to what it was /%postname%/ and all is good, but the same 4 pages will not open.
Then Idid what you suggested esmi, but this did not work either.