Are there any recommendations from professional or academic associations on maximum class size for STEM courses? I read here that some professional/academic organizations (Association of Departments of English, National Council of Teachers of English) have released specific recommendations regarding maximum class size for writing courses.

Are there recommendations from a professional association, accrediting body, or other group, regarding maximum class size for STEM courses? (Either STEM in general, or for specific disciplines. I am most interested in electrical engineering and computer science.)
To maximize creative learning, classes should be small enough for close communication and effective teamwork. One of the basic tenets of system
development philosophy is that involving fewer participants tends to reduce complexity and foster innovation. In short, teachers should be encouraged to reduce the size of the classes they manage.

Instead of answering the question, I'll just point out why I think a policy or recommendation on this topic is useless at best, and counter-productive if strictly followed.

Direct recommendations regarding class size are likely to be too specific to be useful in general. The "best" choice in most circumstances is likely to be a compromise between what is practical and cost-effective versus what is ideal for student learning. The instructor and/or their supporting administration are in the best position to determine the optimal class size, ideally with input and feedback from the students.

A quick search turns up a US study and some statistics on the effects of class size provided by the Council of State Governments.

In addition, the following studies might be of interest:

Estimating Class-size Effects using Within-school Variation in Subject-specific Classes

On the relationship of number of students to academic level

Class size effects and the educational production function in Austrian schools

What Do We Know about School Size and Class Size?