It's not in my hand to look at/tear down but I can't see this happening more than a couple/three ways/reasons.
The ejector isn't completely up into the slot in the left side decocker shaft. If it was that decocker wouldn't be moving. It couldn't move.
Or, the spring that pushes up on the ejector is weak as my old diesel K5 and just can't keep the ejector up in the slot.
If the ejector won't go up into the slot completely it's slot width or ejector width (or maybe, position of the slot in the ejector shaft - not clocked correctly and so the ejector is barely fitting into the slot).
If the spring is weak/too short, etc. you could try ordering a new one.
Man, I hate to wait on someone else to fix my stuff if it's something I can do (or something I think I can do). I just worked on my brand new 9MM AR15 this afternoon to "fix" it. I could have e-mailed people/places but I just wanted to get it going. What I did seems to have worked. Live fire exercise next week, hopefully.
Good luck with yours. I do know one thing. Only a couple places will fix it - CZ or you.