Just a heads-up to anyone building out seek/scrub button controls with the TCP API:

If you make a press-and-hold button to rewind/fast-rewind in vMix Replay, utilizing the ReplayPlayBackward and/or ReplayFastBackward functions, for the purpose of seeking a start point for an instant replay playout (with a play button) or the in point for a clip (for a mark in), then you'll want to make sure you do both of these things on button release:

1) Pause (ReplayPause)
2) Correct the playback direction (ReplayChangeDirection)

It is important that you do both things AND in that order. If you don't correct the playback direction, then playing out selected/all events will not work at all. And, if you do these things in the 'wrong' order (changing playback direction BEFORE pausing), then your next play will 'slip' backwards several frames before playing forwards.

I'm not sure this deserves a formal bug report (because pausing BEFORE you change the playback direction is the 'more correct' solution here), but it probably does still count as a bug in terms of that result being unexpected. Being paused, and having the playback direction be forwards, should result in immediately playing forwards next time you ReplayPlay no matter how you got there, and instead it can 'getcha' on air.