Steps to Reproduce
1) Launch PIE
2) Hit Spacebar (This will a badly made Ability that animates into a T-pose)
3) Hit G (this will play a badly made Sequencer that binds the player into a Animation track where they run)
4) Hit Spacebar again. Note that the Character no longer animates and you have something like this in your log: LogAbilitySystem: Warning: UAbilityTask_PlayMontageAndWait called in Ability GA_Test2_C_0 failed to play montage MM_T_Pose_Montage_Test; Task Instance Name None.