Clicks and drop outs- not the right kind MPC Key 37

Hi all, MPC key37, fairly new. I'm running a sequence, only 2 bars, running 8 synth plugs, mix of Jura, Studio Strings and Electric Piano. Also 2 audio tracks (a bass line and guitar line). Not super busy mad playing, fairly easy on the style but getting intermittent pops and clicks, like when your DAW is overloading. The CPU metre is only reading 34%, the RAM (if thats the middle bar) on about 54%. Intermittent, not in a regular place so nothing to do with samples crossing over. Doesn't sound great, is this something others have found?

is your project and your audio tracks stored on an external SD card or HDD or did you save all to the internal mpc key's storage?