Page 117 last 2 points in "Moving Actions":-

"• Reload a medium crossbow. (This effectively allows
one attack every other melee round with a heavy crossbow medium crossbow.)

• Start to reload a heavy crossbow. In total, this requires
3 full Movement Phases to accomplish, allowing one
attack every 4 melee rounds with a heavy crossbow."

Heavy crossbow is noted in both sections, i.e. the medium crossbow section should refer to medium crossbow!