There's a difference between just killing Atheon, and a raid completion. You have to complete every mission in a Raid for it to count as completion. That means that 55 vault openings, 55 confluxes, 150 oracles, 150 Templars, 150 Gorgons, 150 gatekeepers and 150 Atheon's, will total you to 55 completions.

Thanks for the clarification.

U pushed atheon 95 times?