XDJ-RX echo quantize jumps out of time

HI,

My XDJ-RX has worked perfectly since purchase but recently the quantize feature throws the beat out of time when using the echo/spiral FX. It works at first but then after a couple of beats or so jumps massively out of time and sounds awful. The manual tap button seems to work ok but if I want out continue to use quantize for looping etc it resets the effects to quantize each time I switch FX channel meaning I am constantly tapping and I'd rather not add a percussion performance to my 'highly rated' bedroom sets. Becoming a tad annoying now. As I am writing this, it has occurred to me that it seems to have become an issue since upgrading to Rekordbox ver. 6.0 (which I only use in export mode).

Any ideas?