Logic Pro X M1 playback problem (random intervals of silence)

Hello community,

I've been using Logic for many years and have never experienced a problem akin to this. I've just bought a new M1 iMac and installed Logic X (from the app store) - a new set-up intended for mixing an album.

A lot of the plugins I use do not have native M1 support (Sound Toys for instance) so I have to run Logic through Rosetta 2 - I don't know whether this is part of the problem. I've updated the OS to the latest version which as of now is Big Sur 11.5.1.

The problem is this: projects which run absolutely fine on my Intel 2018 Macbook play back in my M1 Logic set-up with desultory pockets of silence. The playhead continues to move but sound will just cut out for a second or so at sporadic intervals along the track timeline. It's absolutely nothing to do with the audio and depending on when I start the playback, the silence will occur in totally different sections. I also rule out the possibility of it being a CPU issue since the iMac should way out-perform my old Intel Macbook which plays the projects with no problem.

If anyone knows what's going on here and could be of assistance in resolving the issue I would be very much obliged!

Many thanks!