QCTools does not generate functioning output.mkv when using ffv1

[marshalleq]

When running qctools manually, the following is output to console:

[matroska,webm @ 0x13f804e10] Could not find codec parameters for stream 2 (Attachment: none): unknown codec
Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options
[matroska,webm @ 0x13f804e10] Could not find codec parameters for stream 3 (Attachment: none): unknown codec
Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options

There is a jpeg report generated but the qctools mkv file is unplayable.