Entity Revisions not showing?

Do you have show_revision_ui = TRUE in your annotation?

@bbu23 - yes, I do have that annotation.

I was able to make some progress by implementing the changes described here: https://www.drupal.org/node/3160443 →

I am now able to see the revisions by going directly to /my_entity/{id}/revisions, but I'm still not seeing the revisions when I edit the entity.

Ah, so you're missing the tab? Do you have the MODULENAME.links.task.yml file, and do you have in the file something like this:
entity.ENTITYTYPE.version_history:
route_name: entity.ENTITYTYPE.version_history
base_route: entity.ENTITYTYPE.canonical
title: 'Revisions'
weight: 20

Though for that you might also need the route entity.ENTITYTYPE.version_history in MODULENAME.routing.yml unless it's already defined there or dynamically in an Html Route Provider.

Progress!

Here's a copy of my code.