So, I'm using the isometric mode for Godot 3.1, and though it seems to otherwise be working as intended, I'm having some unexpected side effects with rendering.

What I think is happening is that every now and again, the tiles are rendered offset to where they're supposed to be by just the smallest amount. It took my a while to notice that there are also horizontal lines that appear in the same way every now and again, and I'm not sure why.
PixelSnap is off, but when it's on I then get these lines which are worse:

For the sprites themselves, filtering and mipmaps are toggled off for importing, they are on lossless compression mode, with no normal maps or other flags. Svg scale is at 0.001
What might be causing these glitches, and how could I solve them? My main goal is to do this type of isometric game, and so far tilemaps are pretty great to work with, but it's little things like these that make me wonder if there are better alternatives.