The hashrate "drops" due to the different effective algorithms in the algorithm-order of X16r. It's not a bug, it's a feature 
I know it's a feature in x16r algo to prevent Asic miners to join mining with gpu miners but i got confused by what member named "S780" mentioned in previous posts. He's claiming to get stable 38 hashrate on Linux OS.This got me confused since my hashrate goes from 20~31
When this value is set high enough to reach over several algorithms of the X16r, then you should get a stable value shown for your hashrate.
I don't remember the command at the moment and have to look for it... maybe something else could help.
In the background your hashrate is fluctuating as usual for X16r but you get a better mean-value shown.