dnd 5e – What happens if the new UA bait and switch maneuver is used for an ally with grappled?

Recently unearthed Arcana class features include the Bait and Switch Fighter maneuver (page 5), which states:

If you are within 3 yards of an ally on your turn, you can use a superiority die and swap places with that ally, assuming you are at least 3 yards on the move. This movement does not provoke casual attacks (…)

The fixed condition states:

The condition also ends when an effect removes the held creature from the gripper's reach or triggers the gripping effect, such For example, when a creature is thrown off the creature thunder wave spell.

Suppose a monster with a 1.80m range attacks an ally, and the fighter is next to the ally at 1.80m. What happens if the fighter tries to turn on the allies with bait and switch?

For a picture format, F is the fighter, A the ally and M the monster