Many requests get answered within a minute. That is great for the member waiting on loads, and frustrating if you were hoping to earn the credit.
Why it happens
When a notification arrives, it takes a moment to open the app. In that time another member may already have opened the request and started entering the loads. If your airline has a lot of members on StaffTraveler, this happens more often.
How the lock works
The first member to tap an open request gets 5 minutes to enter the loads. During those 5 minutes everyone else sees that the request is being answered, so nobody wastes effort racing for the same flight.
If that member closes the app or does not finish, the request is released automatically after the 5 minutes are up and becomes available again.
Improving your chances
Turn on notifications for new requests, under 'Menu' > 'Profile & settings' > 'Notifications'
Add every airline whose loads you can see, under 'Additional airlines', so you see more requests
Check the 'Requests' tab now and then, rather than waiting for a notification
Requests for airlines with fewer members on StaffTraveler tend to stay open longer, so those are often the easiest to pick up.