Using Swagger-UI v3.20.2, we have noticed that when using multi-part/formdata for the request body, that it won't render any of it at all when selecting the "Try it out" feature. See screenshot below:

Whilst in v3.16.0, which I believe was when multipart support was added for OA3 specs, we were able to see that it rendered the section:

The issue with us choosing to use v3.16.0 instead of the later v3.20.3 was that the latter fixed a separate issue which was present in earlier versions. Attached sample snippet of request body:
v3.20.3_multipart_snippet.txt

Please assist. Many thanks.
Rich