Can be for a couple of reasons, if the map is hot you the maverick can mess up the thermal picture it has and misses its target easy way to prevent it is by simply double checking if its locking onto the target ur aiming for, zoom in on the mav screen and when u lock it make sure it locks the target and not something else, get closer if it keeps locking onto something else. If its a hot environment like on persian gulf map ill just pick the cctv mavs because they dont have this problem
If I recall, everything but the D's have it. D's vs H's really depend on the conditions of the map. Generally, I stick with the D's mostly, and then carry H's if I think I need to force correlate to something that can reach out and touch me.
So that triggers "Force Correlate", and it basically tells the maverick to lock-on to the spacial position at the SPI, like the ground, instead of trying to get a visual/IR lock with it's onboard sensor. I can't recall if I said it or not in the video, but not all mavericks can do it.