No reinforcements in wave combat?

[matfestacomics]

I've been playing on Hard - currenlty about half way through Chapter 19 - and have noticed something odd that I still can't figure out. In wave battles are their certain conditions that need to be met in order to have reinforcements brought in or be given the option to continue/flee? In all of the wave battles I've fought so far I've only ever been given these options once. In every other case when the counter goes down the new enemies show up and the battle just continues as-is, no option to bring in reinforcments, flee, etc.

[Aleonymous]

Um, that's weird. Here's how wave battles are supposed to play-out:

A. If you beat a wave in time

You are given two options:
A1. Fight-on: Reinforcements (from your Roster) are offered; you can swap-out units and/or reposition them on the board. Spawn locations of next-wave untis are shown. When you finalize this intermediate phase, new enemies spawn, the counter refreshes (if there's a 3rd wave) and the battle goes on as normally. If it is the last wave, one enemy should be more beefy than the rest, and be carrying an item (which you'll get if you win the battle).
A2. Flee: Battle ends normally (no re-inforcements, no enemy spawns, no item to be fained)

B. If you do NOT beat a wave in time

There is no option here. Basically, enemies just spawn (from positions unkonwn-to-you) and the battle continues with your Party just as it was (units & positions). If there's a third wave, the timer refreshes. Please note that no "boss" will spawn in this case, so even if you win the wave battle, you will not get an item as prize.

Where does your experience differ from what I described above?