I'm trying to create path grids on a pre-made continent. I manage to place about 2 and when I go to place the next one, it's not there. It's back in the same spot as the last one. When I try to move it to it's proper destination, it's as if there's a barrier keeping the blue thing from moving past a certain point. Anyone familiar with this problem?

Make sure Grid Snap is off.
Also, as you have seen, sometimes the nodes seem to appear in the wrong place (usually at the nearest DoorMarker.) I just delete that one, and make a new one where I wanted it to appear.

I had grid snap off. If I try to place one where I wanted it, it just places it at the last spot again.

Hmmm. never had that problem. I just tried to make it happen, but nothing strange happened no matter how hard I messed it all up.
My Granularity is at 256, and I never "Generate Default Grid"

(and as far as I know, Save User Point does nothing.)

Try reloading the cell. Or even reloading the ESP.

It worked once I added a few then saved, but then they disappeared for some reason. I've tried adding 3 seperate pathways through the town. It seems like every time I reload the .esp, only a different set of those pathways is visible and the others aren't.

Sounds like you're trying to place a node outside of the current cell. With the render window active, hit the [B] key and this will toggle cell borders.

That does seem to be the problem. I never realized I had to stay within the same cell to place these. That's a relief.