Tilemap is sent to back/disappears behind background when I go into play mode or save (video included)

screencap of the problem here

I’m sure this has a simple solution but I haven’t found it answered yet. I have two tilemaps, one a BG and one a middle layer, and everything works when I paint on the middle layer. It shows up on top of the BG.

But if I save the project or open play mode to test it, the middle layer disappears. Seems like it gets sent behind the BG tilemap but the order of the tilemaps hasn’t changed. Also of note is that nothing changes even if I reorder the tilemaps, and the only way I can make the tilemap "reappear" is by ctrl-z undoing my last action. At a loss, any takers?