Order in Layer not working for Particles

Hi everyone - I have an issue with the Particle System, more explicity with the orderring of the effects.
I’m doing a Puzzle Game and the puzzle piece to the right does always overlap the particles of the current piece.

Example:
If Piece #2 executes the Particles (which are in the Puzzle Piece Prefab) Piece #3 overlaps the effect of Piece #2, whereby Piece #1 does not overlap the effect of Piece #2.

Screenshot:

So, the SpriteRenderer (which renders the piece itself) has “Order in Layer” set to 10, whereby all Particle Effects have the value 20 in “Order in Layer”. I also tried to add a new Sorting Layer on top of the “Default” Layer - but no effect.

Has somebody a clue what is going on here?

Thanks for help!