Colt style 9mm magazines have a very small engagement area relative to 5.56mm magazines.
The magazine catch is independent from the adapter. Occassionaly there is a problem with the magazine catch not going deep enough to engage the magazine. Usually this is due to a magazine catch machined too shallow, the pocket for the magazine catch can be machined improperly as well.
Rock River Arms makes magazine catch that goes deeper.
9mm Magazine Catch - 9MM0099