I suspect this is a feature and not a bug because the recording has to be embedded inside the the layer in a way that is not revealed by keyframes, because
as opposite to other recording methods such as motion sketch or puppet pin recording, it does not create rove across time keyframes, but simple 2 linear keyframes.Â
if you use the start or end parameters with linear keyframes, they will still be in the same timing fashion you recorded the stroke with. opening CS6 exhibits the same behavior so this feature was consistent in the last 5 years... so this supports my guess this is a feature not a bug.
my advice to you is leave the stroke you painted as revealed, copy the path from the path parameter under the the collapsed brush parameter, and paste it into a shape layer path and use a stroke width and trim path to reveal as the alpha matte for the brush stroke. either that or paste the path on a mask path and use the stroke effect. if you use a mask path you can also do this on the same layer.Â