I was doing some animation work for a major project when I noticed something: Blender isn't exporting certain bone modifiers properly with the animation.
My case here is that I wanted to adjust a Valve animation for the Soldier robot, the Kazotsky Kick. The elbows looked bad so I decided to whip up a rig and correct that, but I ran into a problem with my setup. I imported the original animation as a separate skeleton and used modifiers to make some bones copy location/rotation where necessary from the other skeleton. The problem is, the exported animation when compiled only shows signs from animation work I did to the skeleton myself like moving certain elbow helper bones around, not any of the other transformations it should have copied from the original animation.

The only way I can think of fixing this for the moment is by applying visual transformations to baked keyframes, which is fine for a small two second animation or something, but this is the Kazotsky Kick. It's 352 frames long. If this can be fixed (I would imagine it could somehow), I would greatly appreciate it. The only other alternative I can think of is trying to copy the individual keyframes for those bones back onto the new skeleton, which would be a huge pain.