How to Identify WHICH gstreamer plugin is missing

SoundConverter 3.0.0 installed from Fedora 30 repository, with plugins bundles "base", "good" & "ugly free". Fedora package "flac" (& dependencies listed in DNF info) is also installed, implementing command line "flac" (coder/decoder for FLAC format). Trying to convert some .WMA sound files to .FLAC. When attempted I'm told:
gst-core-error-quark: Your GStreamer installation is missing a plugin. (12)
gst-stream-error-quark: internal data stream error. (1)

Is there more detailed information about what plugin is being requested that is missing?

The command line transcript reads, early on:

error: gst-stream-error-quark: Internal data stream error. (1) (giosrc location="file:///.../Yes/1%20-%20Roundabout.wma" name=src ! decodebin name=decoder ! audiorate ! audioconvert ! audioresample ! flacenc mid-side-stereo=true quality=8 ! giosink location="file:///...Yes/1%20-%20Roundabout.wma~682102~SC~")