VDA does not recognize input device (microphone) in HDX session. Teams can see audio devices but OS only sees speakers.
There are no policy settings denying audio or microphone redirection
The VDA was installed with the Secure Defaults option which blocks certain redirection technologies regardless of the default policy settings for these.

Enabling the policy setting Client Microphone Redirection explicitly and setting to Allowed permits microphones to redirect into HDX session
VDA does not recognize input devices (microphones) in HDX Session.
Teams can see audio devices but OS only sees speakers.
https://docs.citrix.com/en-us/citrix-virtual-apps-desktops/policies/policies-create.html