Sidechain not visible or working (w/AAC in .m4a audio)?

On a new project, dragged three channels of audio (in this case, two of them are AAC codec in .m4a files) onto the timeline, went to the Fairlight page to set up ducking via the sidechain. Put "send" on track 1 and 3, and "listen" on track 2 with the compressor turned on.

When playing, I can see no sidechain signal in the graphic display, nor hear any ducking on track 2. I attach images below showing the configuration of 'send' on track 3, 'listen' on track 2, and no sidechain signal visible.

Suggestions?

sidechain fail1.jpg (148.22 KiB) Viewed 1613 times

sidechain fail2.jpg (134.09 KiB) Viewed 1613 times

sidechain fail3.jpg (31.18 KiB) Viewed 1613 times

I should add for completeness that both track 2 and track 3 audio are at 44100 Hz.

The track 1 audio is AAC codec in a .mp4 file that was previously rendered from DR.

It looks to be set up right...the sidechain doesn't appear in the meter on the compressor anymore, it shows up in a sub bus in the bus section. Over the right side of the screen you will see the bus meters for bus 1 and 2 etc, if you drag them to the left you should see a bus called 'sidechain' which will show the signal. It should also show in the bus assigns for the channels as 'sidechain' when you switch send on.
With the compressor that is listening, keep in mind it is reacting to the level of the tracks sent to the sidechain not the track it's over, so you may need your threshold to be lower...if you turn the threshold all the way down do you get gain reduction?

This is in 17.2

Andy, I appreciate the help, although I am *puzzled*. I have Studio 17.2, and when I pull the Bus1 left side edge out, nothing appears. If I go to Fairlight / Bus format / Add bus, then I can pull out the edge and see a Bus2 as I would expect. But there is no Sidechain bus listed, and none pulls out to appear.

Is there some other setting that I may be missing?

To add to that...
When I toggle "send" on/off for track 3 for example, in the Fairlight mixer column for the track I see a "bus2" appear in the outputs list... but there is no bus2 defined (in the menu / Fairlight / Bus format, nor when I try to "pull out" the list of busses on the right side area that you referred to. I don't know if a "sidechain" entry should be appearing instead of Bus2? (I see what appears to be a green 'sidechain' in your example image)

This is on a PC (not mac); I'm hunting for any reason that our 17.2 displays would be different.

sidechain fail6.jpg (11.35 KiB) Viewed 1331 times

sidechain fail5.jpg (21.17 KiB) Viewed 1331 times

sidechain fail4.jpg (28.3 KiB) Viewed 1331 times

sidechain fail7.jpg (42.47 KiB) Viewed 1331 times

Interestingly... I was able to get to where Andy is by the following:
* reboot and restart DR
* De-select all Send, and all Listen entries
* Re-select Send, re-select Listen

Now the green Sidechain shows (including in the Fairlight / Bus... menus)

Appears there is a bug in there somewhere on the handling of busses / sidechain settings.

sidechain fail8.jpg (149.87 KiB) Viewed 1283 times

Hey Wes,
yeah I did notice your bussing looked different to mine. I had to check to see if I was on a different build, but I am 17.2 build 11 on Win 10 as well.
Your bus assigns look to be going to and listening to a sidechain sub bus, but it doesn't seem to have created the actual sub bus itself? Weird...
My bus assign and format look like this :

DaVinci Resolve - vo record 23_05_2021 10_20_32 AM.png (11.23 KiB) Viewed 1275 times

DaVinci Resolve - vo record 23_05_2021 10_19_55 AM.png (14.28 KiB) Viewed 1275 times

That green 'sidechain' bus is automatically created when I put a channel compressor into either send or listen, doesn't matter what order I do it in.

The only difference I can see is that I'm using wav files and you're using compressed audio files. All my logic says this should make no difference, if you can play it on the timeline then it should work. Have you got any wav files you could try to rule it out? Maybe create a new project with 2 tracks of wav files, put one into send and one into listen, see what happens? Beyond that I can't think of anything other than some sort of install glitch, but I'm far from an expert. Maybe Reynaud will see this and chime in, his knowledge of the inner workings goes far deeper than mine. IT may be something simple that I'm not aware of...

I think I was posting while you were and missed that you got it working...computers....no logic...