Audio dropouts / UR22 / Live 10

Hope someone can help… Running Ableton Live 10.0.5 on OSX 10.13.6 High Sierra on 2018 MB Pro 15", i7-6 core, 32GB RAM, 512GB SSD, and UR22 both mk1 and mk2 alternatively connected directly to mac via USB-C cable, driver 1.10.2. Live us running 44.1k, 512k buffer. Live arrangement is all audio clips (loops), and I’m getting unpredictable occasional audio dropouts, about a second long, with CPU meter never going above about 20%. Very difficult to reproduce, seems random. All other programs exited, wifi off, etc etc. Any ideas anyone?! Ableton support didnt really offer anything of use beyond basic checklist to reduce my CPU load… Got a gig this weekend and i just know it is going to let me down…!! Thanks in advance for anything else I can check.