I'm not sure about sidechaining, but if anybody is wondering about Side Chain Compression, you can set that up with db Audioware's Sidechain vst. It's a vst2 plugin and the new version is 64bit.
I was wondering for years how to do this, so hopefully this helps somebody in the same situation.
Basically- you add 2 busses to the mix, ie- Bus A and Bus B. -You add the db Audioware vst to both Bus A and Bus B using the bus's "Edit Insert FX Chain" buttons. -At the top left of the vst there is an "External Trigger" switch. Make sure this is on for both Bus A and Bus B's fx. -Set Bus A to "Mode: Send", and set Bus B to "Mode: Receive". -Run your trigger (ie- your Kick Drum) through Bus A -Run anything you want compressed through Bus B. You can control how compressed your target tracks are with the Thresh/Ratio/Attack/etc knobs, but the Thresh does most of the heavy lifting. ***If you want to set up a silent trigger (so you can have a pulsing bass line without hearing the kick that's compressing it) you can turn your Bus A volume all the way down to 0db, and toggle the "Pre/Post Fader Insert FX" button.
the Audioware plugin definitely works, I've been using it in Vegas for a few years. @anthony-james it might be worth checking for an upadte to the plugin that may have resolved your previous issue. For me I always found it had a huge issue with delay between the input track and effect on the output track making it essentially useless for music production. :-/
In reality it doesn't resolve the issue that Acid / Vegas doesn't have proper routing that would facilitate side chaining and many other workflow enhancements. This is currently already on the feature request thread on the beta forums, and has been requested for years prior.
At this stage though if I need to sidechain anything I will just use Ableton live and rewire it into AP8 or export a wav file from Ableton live and import it into acid... I am doing my kick and bass sources this way.
I agree entirely about AP8 needing proper routing capabilities... I don't want to have to rely on just one compressor for sidechaining duties.
There are also a heap of plug-ins that rely on the ability to route audio and midi to any source... Jam origin Midi guitar, iZotope stutter edit etc are just some examples.
Well I think side-chaining will arrive together with VST3 support. I've found workarounds for sidechaining in Acid. Just use DDMF Metaplugin vst - it comes with another vst called "send it" - you send tracks to metaplugin and you do sidechaining inside it. Works fine.
Also I've been using midi plugins in Bluecats Patchwork vsti.
I know - these are just workarounds. But they work :)