Non-linear transitions in timed frames cause the Player to break in the following frame
Setting a non-linear transition (bézier, ease-in, ease-out) for a timed frame causes the div for the place display engine to end up with an invalid class name in the next frame, making all characters disappear from the screen and irreparably breaking the player until the trial is reloaded.
A trial in which this effect is demonstrated can be found here.
A pull request that fixes this issue has been submitted. I apologize for not catching this bug in initial testing.