Delay Compensation erratic behavior

[wyman]

Hi all!

In the past couple of months, I have been having some really odd behavior involving delay compensation. Start a mix from scratch, finish, everything great. Close it. Start next mix, finish, everything is great. Go back to first mix, and there's some serious flamming happening in the drums. Delay Comp light is green, but it is clearly flamming.

My system:

Mac Pro Mid 2010 3.33 6 Core
OS 10.10.5
32 Gigs ram
PT HD Native
Pro Tools HD 12.5.2

I also have a UAD Octo PCI card.

The details:

-I do some pretty elaborate bussing, and the tracks upon which this is occurring are the furthest from the actual mix bus (maybe 4 or 5 busses deep). There's also some parallel send and return stuff going on, some of which involves the UAD card, so there's some serious delay compensation going on, north of 15000 samples.

-I notice it very clearly between a recorded drum and a layered sample

-Sometimes simply closing the session and opening it again fixes it, but upon further troubleshooting, I can fix it by deactivating plugins (control command click), and reactivating them, but not always, and sometimes, it takes a few tries of deactivating and activating for it to right itself.

-In some instances, I can definitely see the numbers in the delay compensation display change, and the culprit tracks definitely have different values when they sound "right" and when they don't, so it would appear that something is erratically reporting delay compensation.

-Deactivating and activating the plugin while the Pro Tools is rolling seems to increase my odds of getting it to sound right.

-It's usually off by about 2000 samples in this session, which is 88.2 32 bit

-That said, it has also occurred in sessions at 48/24

-At first, I thought it may have something to do with Drum Leveler, as we recently installed it, and it brings a fair bit of latency to the party, but I just had it happen on a session with no instances of it.

-Here's a super nerdy detail: In these instances, I have two microphones each on kick and snare, feeding a bus, then a sample. The sample and the "mic" bus then feed another bus (the reason for this is to be able to easily eq the sample or the mics separately. When I take these sources out and feed the main output, they're fine, and the mics and the sample show the same delay compensation. And I can gradually put them further back in their busses, and they show identical delay compensation, until they get to where I initially had them in the mix, at which point the mics show no delay compensation and the sample reports about 2000 samples - about the same amount of time as the offset causing the flamming. This really puzzles me - when I have these tracks - one aux fed by the kick miss, one audio track with the sample - feeding the stereo outputs, they report the same delay, but five busses deep, the audio track with the sample has an additional 2000 samples of delay compensation, even when I load the session with no plugins and deactivate the sends.

So clearly, there's some erratic stuff going on with delay compensation reporting and busses. Is there a limit with how deep busses can go? - in this case, I've got five busses between the source audio and the final output. I've been using this routing for a decade, but never with this much delay compensation. Anyone else experience anything like this?

Apologies for the long post. Wanted to provide as much info as I could.

Cheers,

wyman