My paratrooper repeater developed this sort of problem. I would call it failure to cock. That is the process of breaking the barrel until the piston engages upon the sear ( part of the trigger mechanism) ready to be loaded and fired.
There can be many reasons but in my case a pin within the main mechanism wore out and the looseness stopped it cocking.
More often the sear can wear or springs can weaken. Hopefully someone can offer further advice.