I'm stumbling across a file corruption bug regularly with "complex" simulations, where the simulation is calculating ok, and the renders are ok, but switching to the "Page-Builder" results in a crash. As a side-effect of the file corruption, a view with the name "page builder" is being shown in the "Model" tab.
After the review of the corrupted simulation files by your technical department, the page builder "view" has disappeared.
A potential workaround for the program crashing is:
-->> If no page-builder view exists, automatically create a new "page builder" view.