Alen,
I have been running into a similar situation with beta 4 of Hyperion.ng on a pi zero w. The rpi_ws281x library test worked fine but hyperion couldn't start the device driver.
I tried all of the suggestions from the rpi_ws281x readme found here https://github.com/jgarff/rpi_ws281x but no improvement. I tried compiling hyperion.ng with the latest updates to rpi_ws281x, but still no luck.
The last fix I tried was detailed in this closed issue on the hyperion.ng github repo. Essentially, hyperion needed to be run as root rather than as pi. It doesn't go into detail as to why, but gives the commands to change it persistantly. This finally seems to have done the trick for me. I havent tested it fully to see if everything is working, but hopefully it will help.