It has come to my attention that old replays (e.g. from 3628, 3621) most of the time desync within the first minutes even though they worked fine before. One of the patches between 3629 and 3632 seems to have changed something that does't get reverted back correctly when launching the old replay.
While this bug has pretty low priority, it does make most of Sheppards tutorial-replays useless.