Dapper.Contrib - Get and Insert methods fail occasionally(!) when [ExplicitKey] is used

We have a table with a SqlHierarchyId primary key, and on some occasions InsertAsync on it fails with "Cannot insert Null into Id field", as if the key isn't marked with [ExplicitKey] (it is):
https://stackoverflow.com/questions/49669149/dapper-contrib-insertasync-fails-to-insert-an-hierarchyid-key

It starts happening randomly and then stops happening randomly with the exact same data. Most of the time InsertAsync work just fine, and I have no idea how to reproduce the issue.

Get and GetAsync exhibit similar behaviour for complex keys. We have this problem with SqlHierarchyId, and the topicstarter with Guid key, but the exception is the same ("GetAll only supports an entity with a single [Key] or [ExplicitKey] property"), and again, it happens rarely and randomly, and is impossible to reproduce:
https://stackoverflow.com/questions/45880051/dapper-contrib-only-supports-an-entity-with-a-single-key-or-explicitkey?rq=1

The "solution" in both cases is to wait until the problem is gone (for me it's usually gone after 10-15 attempts) or simply use QueryAsync/ExecuteAsync instead, but that doesn't look like much of a solution. Is there any chance this can be looked at?

Thank you in advance!

Start with the InsertAsync, Get, and GetAsync paths that inspect [ExplicitKey] and complex keys, using the two linked Stack Overflow reports as reproduction context. Investigate why the same data intermittently produces the null-key and single-key errors. Done means the behavior is explained and the affected operations handle SqlHierarchyId and Guid keys consistently.