In-Battle BGM flicks between battle and field music randomly

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Thread name: In-Battle BGM flicks between battle and field music randomly.
Time: Monday 27 October, 2014 ACST (Been happening since last maintenance)
Frequency: Frequent
World name: Excalibur
Character name: Roxas Keyheart
Class/level: BRD 50
Party or solo: Both
Race: Lalafell
Area and coordinates: Multiple Zones
Steps:

• During FATE's and Hunt-Marks, BGM will switch between field and battle music constantly even though it should be battle music. Player Character is clearly in the battle zone and aggro'd (not near the edge of the zone or FATE) so it should definitely be battle music at the time.
• Music will switch between battle music and then the field music (for the zone) constantly - for about 3-5 seconds of BGM intervals each switch until battle is completed.
• Occurrence seems to be intermittent, but focused specifically on Hunt marks and FATE's (Although I haven't attempted other battle types such as Leve's, Maps, etc.)
• Some FATE's seem to be fine, but others are not. This changes though, so one fate which may have the issue might not the next time it spawns, but may have it the following time. This is true for Hunt marks (A and S) as well, but harder to determine.