Sometimes the track blueprint will randomly turn sideways in my inventory and then all blueprints that I place will be perpendicular to the direction that it would be expected to place. I've been trying to find info to see if this is an intentional mechanic that I just don't know how to use, but I've been using the latest 1.12.2 version since it came out a week or so and just started having this issue last night.

A picture is attached to show the issue.

When this happens, does stair placement also go funny?

Yes it does! Just tested the stairs right now, hadn't even noticed that before. If I place a weird sideways blueprint and then reopen the game, the blueprint will be facing the correct direction.
Buggy Version:

I placed the stairs in the same direction that I placed the track, in line with the correctly placed track at the bottom.
After Rebooting, not replacing the block or changing anything:

Interestingly enough, despite the stairs being placed the wrong way in the first place, they don't revert to the correct direction after rebooting.

Another interesting bug while testing! If I place a slope (not a blueprint, a real track) while the bug is happening, then the track still faces the wrong way, but whatever bed I have selected works places in the correct direction. I tried to get a screenshot of this but the glitch just won't happen! Sometimes it'll happen every 3 minutes, sometimes I can try and make it happen for a half hour and get nothing.

Cellman_XM8 found a case to reproduce it!

I think I figured out the condition that causes the blueprint to rotate when going through snow. Whenever the side that snow gets plowed to changes, the blueprint will rotate. In the first inventory slot you can see the blueprint rotate each time the side is swapped. https://gfycat.com/gifs/detail/ShallowLeafyBushsqueaker

EnumFacing[] horiz = EnumFacing.HORIZONTALS;
if (Math.random() > 0.5) {
    // Split between sides of the track
    ArrayUtils.reverse(horiz);
}

I might be an idiot

That would make perfect sense because I stopped noticing the issue right around when I got past the snowy mountains!