In our game Ultimate Mining Tycoon, players can dig through a mine, Minecraft style, with the blocks consisting of re-textured Wooden Planks and Brick terrain that are destroyed when mined and then generated around the mined location. Sometimes the generated terrain blocks have no collisions, and characters can walk right through them. This effect is limited to specific blocks, and is only on the client - other players will still collide with the blocks. The game previously deleted terrain locally and generated it on the server, but now all terrain is generated locally, with no apparent effect on the issue. The effect seems to happen randomly, and we’ve not been able to identify any specific cause.
See the drive link in private content for video examples. Note that after the characters walk through the block the game’s anti-cheat either kills them or teleports them back to where they were.
A private message is associated with this bug report