Divi Page Builder doesn’t appear on the active page, this might be another Divi Builder problem which doesn’t work when you’re using it. To fix this problem, then please follow all of this guide to fix this problem, then please follow all of this step
Clearing the cookies and cache
Clear Your Brwoser data,
Check and remove plugin that conflict with Divi
Go and activate safe mode.
Activate classic editor and the new Divi page Builder experience.
If it didn’t really work for you, go to Divi setting and click Theme Options, choose Builder, click Advanced and then click Allow Classic Editor. Don’t forget to Save Changes. This will fix your issue significantly.
Activate the current Divi builder experience and enjoy new Divi page builder on the backend.