did you find a solution to this problem within gnuradio? I encountered the same problem when trying to process METEOR-M2 within gnuradio with the Viterbi algorithm.

I used the ccsds27 library decoder, but when checking with the medet program, there was nothing that indicated the correct operation of the Viterbi algorithm. Although the sync words were decoded correctly. I also tried to use the FEC decoder with the Viterbi algorithm config, but nothing worked either.