Thank you for writing in, please do a test for a plugin conflict. You can do this by deactivating all third-party plugins, and seeing if the problem remains. If it's fixed, you'll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.
Pro has a Header and Footer builder, make sure you're not switching between builders, when editing a content, do not click any element on the header or footer or the builder think that you're trying to switch to the header/footer builder.
Pro - Header and Footer Builder Introduction