I mentioned this a while ago
Following changes to Pi firmware/kernel, the DMA channel 5 is not reliable for use anymore. Other repositories have changed to use channel 10. https://github.com/jgarff/rpi_ws281x/pull/266/commits
I've been running 3 of my Pi on DMA 10 (1 new Pi3B+ and 2 older PiZeros running Jessie) for 2 months now without any issues so I'm making this pull request now