The problem is because the fixtures in that module are not loaded by the fixture manager at the time the pytest_pycollect_makeitem method is run for our AnnotatedFixturePlugin.

This was also a problem for fixtures using the @pytest_annotated.fixture that I worked around using importlib in AnnotatedFixturePlugin._resolve_from_type to import the module and pass it to the fixture manager to parse.

Here is a similar work around for this problem that works.

diff --git a/src/pytest_annotated/__init__.py b/src/pytest_annotated/__init__.py
index 234ab3b..e5d5225 100644
--- a/src/pytest_annotated/__init__.py
+++ b/src/pytest_annotated/__init__.py
@@ -100,6 +100,11 @@ class AnnotatedFixturePlugin:
         if self.fm is None:
             self.fm = self.pm.get_plugin("funcmanage")
             assert self.fm is not None
+            builtins_mod = importlib.import_module("pytest_annotated.builtins")
+            self.fm.parsefactories(
+                builtins_mod,
+                None,
+            )

I expect there is probably a better way to deal with these issues, but I haven't had the time to figure it out yet, so would be fine accepting this as a solution for now.