'Preview changes' not working

I deactivated all the plugins to check which of those had in conflict with the ‘Preview changes’ button. I activated the plugins one at a time and when I activated this, I clicked the ‘Preview changes’ button but unfortunately, the changes weren’t applied to the post in the preview. But when Exec-PHP is deactivated, the ‘Preview changes’ works. I need help.

https://www.ads-software.com/plugins/exec-php/