Blended speech/lip animation not affected by speed control

[em-ri]

When using animation blending with any of the lip movement animations (e.g. speak/normal_long), speed control does not seem to affect them properly. If animation control speed is slowed or increased, lip movement continues at normal speed, and if speed is set to 0, the animation will reset to the default expression (sometimes after very briefly continuing as normal).
The same effect occurs if the lip movement is enabled through the vanilla Gpose interface, instead of Brio animation blending, and then speed controls are applied.