There's no error or stack trace -- just that request logging does not work.
When _find_filterer_with_filter iterates over the handler/logger list (which contains weakrefs), getattr on "filters" will return an empty list. Thus, it won't find any filters with RequestFilter in them, and thus won't add per-request to those either. This will cause the initial RequestFilter to be applied, which doesn't have a request object and all fields will be replaced with the default "-" value.
Looking at Python repository, here's the relevant information: