Custom Page Type Corruption

I have been having some issues with my custom page types. I have used these types extensively without issue until a recent upgrade:
Core Version - 9.3.7, php 8.2.18

An example: I create a page based on a certain type, choose a thumbnail and when I press ‘Edit Mode’ it goes to a “not authorized” page and the toolbar disappears.

In a similar case in the recent past, I was able to solve the problem by creating a new custom page type. I am tempted to simply rebuild all my page types. I wonder if there is any way to get rid of the old page types, delete or hide them, without breaking the existing pages that are based on those types.

Any ideas would be appreciated.

I have not experienced your problem and don’t have a solution. But lets rule out the trivial.

As a first stop, look for un-matched tags using a tool such as the w3c validator.

Then run through your problem sequence with the browser dev console network tab open and recording documents, so you get a network history of what is happening.