Many accrediting/evaluating agencies do not consider writing teachng case as part of research whereas it involves more work as one has to write teaching note along with the case.
Unlike research which is real reasoning and towards a meaning full end, the Case writing are mere narrations of settings, practices, problem stain and solution in a particular or specified area, giving a big picture. while when analyzed would throw various components which are more individualistic and derived (eye of the beholder)
Action research as a research practice is often undermined by some but it is an essential part of professional development. There are some contexts where action research is used as a tool for curriculum reform efforts such as Zeichner's study:
It is also widely used in educational settings for school-wide action research project, which are wide-scale research studies. For further information, you may refer to "Schoolwide Action Research" by Clauset, Lick and Murphy (2008)
I don't see any issue here as long as one follows or observes necessary protocol in disseminating academic works, whether derived in practice or through rigorous research methods. I STRONGLY agree with Abdalla that 'it should be refereed'. In fact, such writing must be written academically; and it does not matter if you are a classroom teacher or a professional researcher. Note that research is research as long as proper protocols are maintained and followed rigorously, be it 'Narrative Writing' or 'Writing Teaching Case' or 'Action Research' and so on.
These days, Action Research has been recognized as a sound method of research though positivist and post-positivist still raise question on its validity. In the field of management research, both case study and action research have covered lot of ground. Why then a teaching case which can use both the case study method as well as action research should not be considered a sound research?
wether professional work is to be considered as (scientific, teacher-) research or als inquiry depends on its scientific rigor and practical relevance. Read Schön (1983), Wolf & Rosenberg (2012) and for example Vanassche, E., & Kelchterman, G. (2015). The state of the art in Self-Study of Teacher Education Practices: a systematic review. Journal of Curriculum Studies 47(4), 508-528.