Hey! One friend in our group had this issue a lot of time but mostly at specific places (ex. Apoptes encounter). We found a reddit post (https://www.reddit.com/r/destiny2/comments/1pkeudn/anyone_else_having_disappearing_rifts_in_pvp/) after we went to the map and tried different things and managed to replicate the problem very consistently. If you are running into the wall and try placing the rift as such a lot of the times (at specific walls) it places the rift under your feet but one floor below. I think it comes to this result cause the rift's casting place (aka. the center of the rift) is calculated based on your motion vector at a frame which would place you in the wall on the next frame. The rift is cast on the other side of the wall where you don't have the floor surface under your feet that is why it will be on the surface below. But your character won't get on the other side cause the game detects the collision between your character and the wall and pushes you back but the rift's cast is already calculated at that point (this method is in a lot of game engines ex. Mario Kart). One workaround could be to get your position at the input/button press frame as the cast location and leave the motion vector calculation behind but don't know how big of a difference that could be when the player casts while sliding (the rift would be behind you in this case sometimes) or is it feasable at all. If I could help with this investigation I'm happy that it worked. Have a nice day!