The issue with WordPress 4.9 and OptimizePress has been addressed with the latest release of the plugin.
You have to renew your support agreement to get the update.
I have the same issue with OptimizePress. The 4.9 update totally disables Live Editor. Not even their Support option will open upon clicking.
Restoring to the prior version of WordPress fixes the problem temporarily. I have opened a ticket with the OP support desk.
