"A system error occurred during event movement." in quest "As the Heart Bids" as BLU

Date & Time: 6 August 2024 16:51 UTC+2 (and before that)
Frequency: Always on attempt
World name: Shiva
Character name: Edivad Avlis
Retainer name: None
NPC name: Thon Sul
Monster name: None
Class/Level: Blue Mage/Level 76
Party or solo: Solo
In-game time: 14:19
Area and coordinates: Il Mheg X: 12.2 Y: 33.1 Z: 0.7
Housing: None
Steps:
1. Progress through first five steps of the quest on Blue Mage, up to 6th step "Speak with Thon Sul again" which should lead to a solo duty battle.
2. Watch or skip ensuing cutscene.
3. The player is returned to in front of Thon Sul, as before speaking to her.

Connection Specs
- Type of internet connection/provider: Wired/Vodafone
- Modem maker/model number: AVM/FRITZ!Box 7430

Additional information: This is the quest after maxing out Rank 6 of the Pixies. Logging out, logging into another world, going back to home, didn't fix this behaviour. Attempting the quest as Reaper did, after the cutscene the solo duty is accessed; going back to Blue Mage made the error occur again. However, there is no indication this quest shouldn't work as Blue Mage.