~2.5 months ago nothing was broken, nor in radxa kernel, nor in ZFS, so more like “it was broken” in the past 2-3 months, if ppl right now can’t build master zfs on rock5 
Use ROCK 5 as NAS?
Aha, then this general Rockchip upgrade to .110 messed things up. Some features were fixed, some broke, completely normal …
Just the regular nasty effect of using a heavily forked kernel It’s impossible to benefit from features and fixes at the same time because new fixes will constantly need to be adjusted still they stop breaking other stuff.