Assigning powers to quick keys

It's a known glitch. They never bothered fixing it.

This bug was even present in the Mass Effect 3 demo but not in the full game.

Odd, I never experienced this issue although I completed Mass Effect 2 more than 10 times all platforms combined.

In case it might fix it, can you try to repair the game data directly from Origin?

(Right-click on « Mass Effect 2 » then select « Repair Install »)

It doesn't happen all the time. It's mostly a problem during combat, where it's almost 100% reproducable, and sometimes out of combat as well. I've beaten the game over 20 times on different hardware setups and with fresh installations. Many people had this problem and it was acknowledged by BioWare, but never fixed.

Thanks for the clarification fredvdp, I wasn't aware of this.