Updates to less popular trainers or trainers that are working for most can take time if there's a large queue of popular titles ahead of it with many reports, titles that are obviously broken, or a mixture of these and other conditions.
Battletech usually gets some reports, and from my experience, it's in many cases the weird nature of the game mixed with a healthy dose of "did not read instructions", as the options for this game definitely require people reading them to function. Unlike other games, you get in game, activate, hit corresponding num key, and off you go. But there could also be legitimate issues for some that others don't experience, and those get fixed (hopefully) with updated releases. Just a whole bunch of potential reasons why.
Hope that answers some of that.