Thanks for your response. I also reached out to Inertia Sound Systems to get their take on it. It might be a plugin specific compatibility issue.
If you move the first automation point to another location, can you check that Logic effectively spikes the cores and throws the MIDI Sync error at the new first automation point location?
Yes, this happens. No matter where I move the first data point, as soon as the playhead passes over it, the CPU meter goes haywire and spikes a few cores, resulting in a Midi Sync error.
If you create a new track, insert the same plug-in and create automation on that new track, can you reproduce the same issue?
Yes, this happens no matter where the plug resides. I also put it on an instrument track, bus, aux... no difference.
If you create a new Logic project, only one track, can you reproduce the same issue?
I did that for Inertia to show the error. I also recorded a video showing the problem in action. which I'd be happy to dm you if you're interested.