Finisher Animation on Kuva Fortress always the same

[XBaniX]

The Stealth Finisher animation on the Kuva Fortress is always the one from a Nikana (Tranquil Cleave). I tested it with different Frames and weapons on the Kuva Fortress in Spy and Capture gamemode.

Ivara and Scoliac:

 

Ash and Rakta Dark Dagger:

 

Ivara and Venka Prime:

 

And since i read that switching weapons can fix this: