When interrupting the animation to place a party tent, the tent will lay to your feet.

If this spot to your feet is elevated, the tent will be half stuck inside the ground.

You cannot pick up the tent anymore now, and you dont see it in the vicinity, so it is stuck there forever (until despawn?)

In the video you see the buildings I tested it in where this bug occured: https://youtu.be/EuRM3BTBrng (industrial shed blue doors, large wood shed, wooden farm houses)

It also happens at some elevated streets/paths like you can see in the beginning of the video.

When you pack the tent normally on these places, the tent does not get stuck. Only when interrupting the building up.

Have not tested it on 1.13 yet.