Something does not convince me about R-60MK missiles

something doesn’t convince me about the performance of this missile, because I often fire the missiles above M1, and the missile often struggles to stay behind the target which obviously moves at a speed much lower than its maximum, (since the fights take place at low altitude to avoid radar-guided missiles), which is 2.5M (2,981.7 km/h), so I can’t understand why this difference between what is written and what the missile actually does. moreover, he loses the lock with extreme ease, while instead he often prefers to follow the allies rather than the framed enemies (how ironic). Has anyone encountered the same problem?