Differential pair DRC issues galore

I’m trying to lay out what I think is a simple diff pair case: 6.787mils trace, 5mils space. Board requirements are 5 mils trace/space, and my poured ground polygon these traces run through has 6 mil clearance set so that’s not coming into play here.

It seems I can’t avoid DRC issues on these traces, and I don’t quite get why. I’ve tried routing, then push-n-shove to tidy everything up, which results in lots of flags, and also routing with a minimum grid set and then not touching anything after.

Here’s an example image:

In essence, I get a DRC flag saying the traces are spaced at 4.98 mils on the corners, even though the settings are all 5 mils and best I can possibly measure, that’s obeyed.

If I then go into board settings and relax the spacing requirements on the diff pair to 4.5 mils just for kicks, I still get the same exact error (as if I didn’t change the spacing requirement at all).

I went ahead and ripped up all these tracks and re-routed one set with the ultra-fine grid. Now I’m getting a new error: Error: Differential pair gap out of range (...) minimum gap: 5.00 mils; actual: 5.00 mils)

This all sure feels like badly-handled floating point errors in the DRC engine, but I’m a KiCad novice so I’m not sure if this is normal, or a bug, or known, or “this is the workaround I use.”

Any tips from the experienced?

Edit: I’m getting the sense that maybe if I set the diffpair spacing to 5.01mils, that might do the trick in terms of push-n-shove post-route. Edit: nah, that helps, but doesn’t fix.

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Maybe you should consider moving the ground vias 1 or 2 mills away from the traces.

If you zoom way in on the corners where the DRC violations happen, can you see any artefacts there? Any segments from rounding the outer corner or anything similar?
Just a thought; I haven’t had this exact problem myself…

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