Academy students disappear during operations

[Gorbald]

Steps to reproduce:

Build a ship

Add a captain

Add an academy block

Hire some all-rounder crew (more than academy capacity)

Start training them to be some specialist crew (I was training boarders)

Send the ship on an operation (for me it happened during a scouting operation)

Recall the ship. If the bug was not reproduced, send it on an operation again and wait for it to finish (hopefully not needed).

Expected outcome:

Academy students stay in academy. Ideally, if some time passed, then the timer progresses or some of them finish training and become specialists

Observed outcome:

Academy students, including those in academy "queue", disappear.