Divi 5 is a nerve breaking theme!
If the plain page still shows
Excellent. Divi 5 is not breaking WordPress this time.
If the plain page disappears
Then Divi 5 itself is the trigger on this setup. At that point, we stop and either check server requirements or use Divi 4 instead.
Elegant Themes’ current Divi 5 troubleshooting says blank/missing content can come from Divi cache, Theme Builder overrides, or conflicts, and they recommend clearing Divi 5 CSS cache and checking templates before changing anything else