Time: Always
Frequency: Always
World name: Mateus
Character name: Aerden
NPC name: N/A
Monster name: N/A
Class/Level: PLD 37
Party or solo: Solo
In-game time: Always
Area and coordinates: Eastern Thanalan, X: 12 Y: 27

Steps:
1. Accept Quest "Mr. Slipshod and Ms. Uptight"
2. Mount chocobo and travel to coordinates
3. Enter quest battle area without dismounting
4. Battle is not initiated

Not sure if this happens with all quest battles or just this one.