I have confirmed that when The Events Calendar plugin is activated (with or without the PRO plugin activated, as well) PREVENTS posts and pages from appearing within the Hyperlink Browse section of the WYSIWYG editor. Only Events appear within the browse list.
NOTE: I have confirmed this behavior with ALL other plugins deactivated (leaving only your base plugin activated). I have also confirmed this behavior with the Avada theme disabled and the 2011 theme enabled.
When I deactivate The Events Calendar plugin, pages and posts appear again.