Getting super jerky curves

My machine has been working well for years. But this may be the first time I'm cutting something with a spline (although I've cut font paths before without this issue). I'm not sure if I messed up a setting or what. It's been quite a while since the last time I used my router.

I've attached images of the parts I'm cutting, how it looks in simulation (a series of line segments, it seems), and the generated gcode (from the current Fusion 360, although I haven't updated the post processor in some time). I'm not sure if this is a Fusion tolerance issue, or I need to tell it to use some kind of arc move, or my linuxcnc setup is not right (I've attached my .ini file too).

      And here is video of the resulting machine motion.

Ah sorry, had trouble uploading it. Should be fixed now.

Is G61 set by default? I don't see it in the gcode. I think I want to try G64, right?

So, this solved my jerkiness issues, but now I have some strange behavior. *Some* (but not all) corners are getting rounded off, as if G64 were specified without P value.