Custom entities are not showing in entity type dropdown

Support provided in slack; the entity needs a 'path' field. I wonder if that is, or should be, documented somewhere useful for developers? Or perhaps the module should be able to work without a path field, so just working on the path of the underlying route for the entity type's canonical template link? (e.g. /node/X/<pattern>) I think the latter already works (it's certainly implied from the path pattern element description in the supplied screenshot!), so why should the path field be required at all??

Changing this to a bug report, because it's either a bug in the form of an unnecessary (unintended?) dependency, or in the documentation.

@james.williams, thanks for your support. I faced this issue as well, and your solution fixed it.