BIRD 3.3.1 persist option (proto kernel) not working

After upgrade 3.2.2 -> 3.3.1 the ability to leave routes is broken. When stop Bird, all routes are removed from the linux kernel. Conf sample: protocol static { ipv4; route 172.16.0.0/12 blackhole; } protocol kernel { persist; scan time 5; learn off; ipv4 { import none; export all; }; }