Audio Desync (drift) between audio sources

Hello, first, a little bit of context:
I’ve been trying to build a setup that allows me not to use headphones.
Yes, it’s difficult and annoying to fine tune, but i got it to a working state, so its doable.
My current setup is pretty basic really, system audio internally captured by xsplit, microphone input through usb audio interface. No more audio ins or outs to be concerned about.
I adjust latency on system audio to match as closely as possible to Mic “echo”, and after some testing, boom, its done, and it works rather nicely.

Except after some hours have passed there’s noticeable audio drift. It’s small compared to other issues i’ve heard but in this situation even a little bit becomes quite obnoxious. And we’re talking something like 120ms give or take over the course of 3 hours.

It’s not a sample rate issue as all sources are set to 48kHz and i’ve tested to see if OBS did the same, which doesn’t so it must be an Xsplit problem.
I also tried deactivating Wasapi. Nothing.
Then i switched from legacy video to GPU and nothing aswell.
It consistently drifts. Sometimes less, sometimes more.

I can route the system audio through the interface and pre-mix everything into one audio input, but i’d lose separated audio and i can only use multitrack channels as separated audio backups on OBS since Xsplit doesn’t allow me to choose were each audio source goes in the multitrack.
(which by the ammount of times i’ve lately had to fix the audio in post is not a function i’m about to give up)

It also takes me a huge ammount of time to test this and i’m at the end of my patience with an already existing better alternative. It does feel like an xsplit audio pipeline problem.

TL:DR
System audio drifts from Mic audio over the course of hours, noticeable after about 90 minutes (Overlayed), tested all plausible culprits i could come up with (it isn’t a bit rate, audio render engine or video playback engine problem), OBS works fine using same sources so must be an Xsplit problem.

Switching to OBS for main use while it isn’t fixed.

Just thought i should bring this to the forums in-case there’s something i missed. The last post about a similar ocurrence was made about an year ago and i’m on the latest version of the program so i’m guessing whatever problem there is it isn’t solved yet?

So is it the mic or system sound that drifts? If system audio, is it screen capture/game capture you’re using to gauge this? Just trying to work out what audio is actually desyncing and making sure it’s not the video aspect that is drifting rather than the audio.

It’s honestly hard to tell, i applied latency to system audio to sync it up with mic input but since i only have two sources i could not compare to anything. I’d have to do another test and use a video feed to compare lip movement to figure out which one it is.