Been running tracking sessions for the past few weeks with zero AAE errors at a buffer size of 64 (44.1/24) on Mojave with Pro Tools 12.6 on a new Mac Mini. 16 tracks, 4 auxes for headphones, VMR w/ mic/pre modeling on every track. Disabling hyperthreading was definitely the key. Hopefully official support for Mojave will come soon so I can get a little processing power back (haven't needed it so far!)