Soundtoys frequency drop out issue

[joseph.bates]

When Soundtoys plugins are included in my set, I get frequency dropouts at specific frequencies, even if the plugins are deactivated. These dropouts are not visualised in the meters: the master channel reads as outputting audio. When audio is exported, the issue continues.

The dropouts stop if I bypass the master channel and send it directly to the external out. They also stop if I send the master channel to just one channel. The issue occurs across output devices: my Scarlett, my EVO, and the laptop's own output. The frequency dropout moves when I delete a Soundtoys plugin from the channel and disappears after deleting all the Soundtoys plugins.

It's completely bizarre: I've never known Ableton's metering to be wrong! But it's a major problem: I have a gig in two weeks and need it sorted.

Does anyone have any ideas about what I can do? I'm currently trying to replicate the Soundtoys effects with Ableton's own plugins, but it's a real pain.

I am using Live Suite 11.3.30, version 5.4.3 of Soundtoys, and am on OS 14.6.1 on a 2021 Macbook Pro.

[cubane]

Could try to swap between the VST3 / VST2 / Audio Unit versions of the plugins and see if you still get the effect

[joseph.bates]

Thanks cubane: that didn't solve it, but I think I've got further towards the answer. I had one channel designed for recording the master output, which I'd accidentally left routed to the external out. I suspect that I was getting some phase issues or some other kind of interference between the output signal from the master channel and from that channel. Perhaps the soundtoys plugins were causing latency which altered the frequencies effected by the phase issues?