As mentioned above, I'm not sure the Intel drivers actually support hardware flow table offload. I came across a thread on the netfilter development mailing list where the maintainer mentions that the driver needs to implement TC_SETUP_FT and that hw-tc-offload is not sufficient. The thread was discussing the igb driver for the Intel i350, but a cursory search of driver sources I only saw reference to TC_SETUP_FT in Mellanox and Mediatek drivers. It is entirely possible I'm missing something though.