Your mag release height may be too high. Or one side of the release is angled Compare the functional mag to the new ones that are not working. Try a side by side to compare the feed lips to see if the lips are higher on the new mags.
Lock bolt to rear, insert the functional mag and watch how the bolt travels over it as you cycle it. Its relation to the feed lips. Then try again with the new mags that are not working to see the differences.
You may be able to adjust the mags to get them to work with the rifle as is. There may be other solutions but first get a better understanding of why the one set of mags being newer HK mags and presumably to correct specifications will not work compared to the older mag.
Also you mentioned pressing the release but leaving mag in rifle, have you pressed the release partway so it doesnt disengage from the mag (you can gently tug on mag with out it coming loose) and see if the bolt travels then?
If you are pressing the release and the bolt acts fine I suspect the pressure of the mag against bottom of bolt is what is holding the bolt up. When you hit release it is allowing mag to drop the little bit it needs to allow proper bolt travel.