Been seeing this a lot as of late. Partially due to experimenting with launching objects by spawning a cube underneath them.
The issue occurs when I'm the client in a match. There is a flat ungrounded wall I spawn a cube under. The cube and wall break on each other immediately.
This is in contrast to when I play as host. I spawn the cube under the ungrounded wall and it launches it upwards, or makes it flip if closer to the edge of the wall than the center of mass.
I feel like it is simply another downside to playing as the client of the match. It may be due to a certain level of ping, but that'd be strange due to physics being handled by the host?