Unfortunately, this is a bug we haven’t had an elegant solution for.
The details are that the skeletal mesh updates when you move it but the evaluation of the skeletal mesh doesn’t know anything about Sequencer, so it reverts to a T pose. Sequencer doesn’t evaluate to pose it where it should be since the actual frame hasn’t changed. So if you nudge (frame forward/backward) Sequencer slightly, it’ll get back to the pose you’re expecting. That’s not a great workaround unfortunately.
There is a bug here report in case you want to follow it for tracking purposes.