Reqs are unable to used even with the number of levels required. Are only able to open the req menu and select a req but cannot replace current weapon with selected reqs. Same goes for vehicles, armor mods, and weapon load outs.
Have a try at the following general troubleshooting shooting steps:
- Complete a cold reset of your Xbox One by holding down the power button for 10 seconds to clear the game cache. - Reset Alternate MAC Address in system network settings on your Xbox to improve the general responsiveness of Halo 5.The second one above almost always works for me. If they don’t work, then it is most likely a temporary problem with the servers (or at least temporarily worse than they normally are).