Zombie alarm!!
The "weird invisible element" you described is in fact an undead player!
It gets created because the player explosion is interrupted by the CE creating a new element at the player explosion's position in "destructive" mode (replacing anything destructible at that playfield position). So the explosion is removed halfway, leaving an undead, invisible "ghost player" at the same position occupied by the newly placed game element, preventing the yellow emerald above to fall down (even if the new element is empty space -- the "ghost player" is still there, keeping the yellow emerald above in place).
This bug (interrupting a player's explosion that way) should have never happened -- fixed now!
Thanks a lot for reporting this bug!
BTW: During debugging of this bug, I found another bug connected with such situations. You can trigger it when removing the "deadly when touching" property from CE 001, and touching it again: It will cause a player explosion (as expected, because it forces an unwalkable game element at the player's position), but this explosion looks buggy, as it gets restarted when half of the explosion is done, then finally doing the full explosion. It does not seem to have further negative consequences, but is just not correct, so I have fixed this one, too.
. A weird invisible element got created and when ce 1 tries to replace it, it explodes. You gotta download this file, to believe!