"Bind pose" Error when reimporting a skeletal mesh FBX with animation

Heya all,
We've been in the process of iterating on a few of our animated characters on our project and we've been getting the dreaded "Number of bind poses doesn't match number of bones in skinned mesh." error.

To give a bit of info, we're working in 3DSMax, and exporting a single FBX file containing the Skinned character and all animations strung together, separated into clips in Unity. Our FBX's are then referenced in a character prefab in the scene.

We're encountering issues when iterating on an animation or model and reimporting that same FBX file, utilizing the exact same export settings. The model and animations come in fine and are visible in the inspector, but when we go to run the game, we get that "Bind Pose" error. It also seems really intermittent; some of our characters don't have any issues on reimport, while others break.

Any insight into this issue, or how we can best adjust our character pipeline to account for Unity?

Thanks in advance!