Comment 1 for bug 1877900

A workaround is

$ GRC_BLOCKS_PATH=$(find /usr/ -type d -name blocks | xargs echo | tr ' ' ':') gnuradio-companion

which sets

GRC_BLOCKS_PATH=/usr/include/gnuradio/blocks:/usr/share/uhd/3.15.0/rfnoc/blocks:/usr/share/gnuradio/examples/blocks:/usr/share/gnuradio/grc/blocks:/usr/lib/python3/dist-packages/gnuradio/blocks:/usr/lib/python3/dist-packages/gnuradio/grc/core/blocks

That's kind of ugly though and violates my expectations of having software just work straight out of the repositories, or if some additional setup is required it would have been nice to get a message from apt/synaptic.