Phase on plugins and busses. AARRRRGGHH!!

Issue #1: Certain plugins, primarily waves (YES, I KNOW they don't support Reaper yet) but some others as well, create a phase issue when I send other tracks to them, for example a drums bus for sidechain compression. To date, all I've found in the forums is tedious workarounds- i.e. mix the track normally, then mix the bus, measure the sample difference and move the sidechain's audio. This is HUGELY inconvenient, tho, if I plan on adjusting ANYTHING on the sidechain track, like I decide I've got too much reverb, or I think the kick is picking up too much, etc. or I want different EQ or comp settings- I have to Re-render the sidechain track, listen, and if I don't like, adjust and re-render again. Anyone have any idea about how to make this workable? Link to a post I missed? Issue #2: To further solidify my now boycott of Waves until they support Reaper, when I'm working on a big project with lots of effects, I'll start to lose the GUI of Waves plugins. I'll put a plugin instance on a track, and nothing pops up, click on it, nothing. I can pull up the generic sliders via Reaper's UI button, but some Waves plugs are hard to use without the actual GUI. Again, any suggestions or workarounds would be greatly appreciated.

waves does support reaper now actually. Maybe you have some updates?

Several updates to reaper in the past year related to Waves plugs like 5.11 FX: improve support for Waves plug-ins on OSX 5.15 FX: preference option to allow filtering all browser views, filter Waves AU on OS X by default and more recently many tweaks to vst window resizing. But if you have old versions you might be stuck.

Have you tried rendering? Maybe your setup would cause phase issues with any plugins? Does rendering solve it? Are you using VST3? That solved all my Waves GUI problems on Mac. You're not using mono versions of any plugins are you? You can end up with clean audio passing through the right channel and causing phase problems with the effected left channel.

Well, I have a bunch, so I haven't tested them all, but the worst offenders seem to be Waves plugins, and IK Multimedia, specifically T-Racks. Since I'm doing sidechain, I'm mostly dealing with compressors so I haven't really tested much with other types of plugins. What I do know is that when I slapped an NI compressor on the track, it was fine, but with a Waves comp, the phasing/flange sound was horrible. I even tried scooting the audio over one sample at a time which just changed the "flavor" of the phase problem, though to be fair, I didn't scoot it far enough to make a real difference- can't remember how many samples I measured it as being off by- either in the 20's to 50's range or the 200's. I'm just not sure how to proceed. I'd really like a solution that doesn't require me to render the track- I'd like to make mixing adjustments in real time. Have a message to Waves tech support on the GUI problem. Haven't discussed the phase issue with them yet since theirs aren't the only plugs that cause the problem, so I'm guessing the problem is with Reaper or some other component of my system, though I can't imagine what that would be. I do have a manual latency set for my Mackie firewire which I got by running a click out and back in as audio. I have to adjust this depending on my buffer size, but latency settings shouldn't affect plugins should it?

My other thought is that I use a lot of folders, sometimes folders within folders, esp. on drums. However, that shouldn't be an issue if I'm creating a send from individual tracks should it? Any direction anyone could give me on what to test and how would be great.