For what it is worth sound even occurs with the PMC-8 G-11 version.
It started with the v14 firmware update that increased the torque of the stepper motors. Here is a YouTube video that I recorded in August of last year.
Mounts: ES PMC-8 G-11, ES PMC-8 EXOS-2
Scopes: ES ED127 FCD-100, ES Levy Comet Hunter, ES N208CF, QHY Mini Guide Scope, Solomark F60 Guide Scope
Cameras: QHY600M, QHY128C, QHY168C
Misc: MoonLite CFL 2.5 / High Res Stepper / V2 Mini Controller, Baader SteelTrack NT / SteelDrive II, Baader UFC, Optolong 2" L-Pro / L-eNhance, QHY CFW3-L, Baader 2” LRGBSHO CCD
Imaging Software: NINA, APT, SharpCap Pro
Processing Software: PixInsight, Lightroom, Premiere Elements