Printed tracks not sounding like project versions

Hi,
This issue has been driving me nuts recently.

2 Acu gtr tracks. L & R.
I add some processing on both, I’m happy, I want to save DSP, so I render them.
Sound just as they did rendered as they do on the project.
Great
Now…the project gets bigger, I’ve now bussed them to a stereo bus, sent that to the mix bus which has processing on it as well…and again the project is at a point where I need DSP.
Here’s the problem:
I do a stereo mixdown of my acu bus (first I route it to stereo out - which has no processing on it, so that I can route my mixed down acu bus once it’s a wav back to mix bus and all should be good)

Now when I pop in the mixdown wav of the acu bus, route it to mix bus, and add any sends that were on the orig. replicating their setting identically, there is a very audible difference in the sound.

The orig bus with all that live processing sounds bright, and balanced how I want it.
The new wav version, despite carefully seeing to it being identical through routing etc…doesn’t!!

Anyone ever have this problem?
It seems to happen when projects get large and the DSP meters start to let me know I’ll have to begin bouncing/rendering if i want to continue.

Drives me crazy. Doesn’t always happen, but the bigger the project, the more processing the more it seems to happen.
It makes no sense to me, as I take every care and double check my routing.

Any suggestions and extra checks (something I forgot?) are very welcome!!

Hi,

Are you sure you export/mixdown really a dry signal (no Inserts, no Sends, no Channel Strip, no Output bus Inserts, Channel Strip…)? Are you sure you set all the parameters the same after export > import?

Btw, I don’t understand your workflow. Why do you export? You can freeze or you can Bounce if you don’t have enough CPU resources.