I cannot find access to the metadata window when working inside Audio Montage.
Is there something I am overlooking, or is there a reason I only see it the wave editor?

Metadata is an audio-file addition, that depends on the audio file format. This is why you only find it on the Audio file side.

Thanks PG.
So as suspected, I need to modify my workflow.

Actually, there is a trick: when you save a montage template, you have the possibility to associate a file format with it, incl. some meta data. When you create a montage from this template, the meta data will be used, if you don’t change the file format for the output. That is, the meta data will be included with the rendered form of the montage.

Wow. Thanks for that tip.

Best regards,