The most probable cause is that you are not doing your turn close enough to the pocket/curl.
Boards with tails with high rocker and narrow outline work best when they are working in a very powerful section of the wave.
Flatter rockers like on the mana will work best on flatter sections of the wave.
Also, shapes like the Hokua may be more driven with the front foot in turns, try to engage fully the rail and not stall them.
Basically, these "shortboard" shapes need to be ridden like a shortboard: in the pocket, and keeping being "late" relative to the curl: always in a hurry trying to rejoin the curl, rather than leisurely carving ahead on the shoulder.
Or your waves where to weak for the hokua: then you need to pump heavily in turns to generate speed.
Get in "white rabbit mode" !