slog 3 footage color issues in sequence

Hello  
I was experiencing the same thing. I always use an adjustment layer for the phantom lut I use but I was getting weird colors and exposure. 
I solved the problem the long way, and then the short way. The long way: by going into each clip in the timeline, then going to the Lumetri Color panel and clicking on the Settings tab. On "Source Clip" I clicked on "Override media color space:" to Rec. 709.
After doing this I got the proper log look and the adjustment layer with the lut seems to be working well.
Below "Source Clip", on  "Sequence", i didn't change anything. The "working color space" is Rec.709

Then I realized there is a way of doing it faster. Go to the project panel, select all the clips -> modify -> Color. Do the same -> "override media color space" to Rec.709
Hope it helps. 
Leon

First, why are you using the various odd spots they initially put CM stuff into, rather than the full CM controls panel ... Lumetri panel's "Settings" tab. Which has all  the color management options, and if you have a clip selected, even the clip CM settings.

This stuff is all interactived. So that's both where you should set things, and where you can best show others what you've done... as everything CM shows there.

Second ... that clip is not being correctly 'seen' of course. But as "we" can't see what you've done for CM, "we" can't say exactly what the problem is.

Have you set both auto-detect log and auto-tonemapping to on. Then exported to a 'standard' Rec.709 preset?

As if you haven't, well ... you haven't used the CM as it is mainly intended to work. And in doing so, you'll either 'fix' the problem or not. Either result tells us something useful.