[Bug] Heals not hitting targets

[Viviza]

ISP: MTS
Type of Internet Connection: DSL
Internet Connection Speed: ~850KB/s
Date & Time: March 28th 4pm CST, also March 27th but I did not note the time
Frequency: Sometimes
Character Name: Viviza Viza
Race: Lalafell F
World: Ultros
Class/Level: WHM 50
Area and Coordinates: Brayflox (hard)
Party or Solo: Party (4)
NPC Name: None
Monster Name: None
In-Game Time: Not certain

Since 2.2 came out, I've had numerous healing spells fail to work while in the new dungeons. I have not had the issue come up during solo play. The cast will complete and animate on the target, but nothing will happen. The combat log will register a start of cast, for example, "You begin casting Cure" but then nothing, not even a "You cancel Cure" message that would normally come up on the log if I had done something to stop the cast on purpose.

Spells affected are Cure, Cure II, Medica, and Medica II. When Medica II fails it will not apply the buffs to anyone. I seem to be able to land Regen and Stoneskin on targets and they will work normally. Switching targets or pausing for a moment before casting again do not seem to resolve the issue.

It seems to happen for certain periods of time in the range of 5 - 30 seconds in length. During these times no healing spells will hit. Other effects around me (ie. applying/removing buffs, avoiding dangerous areas, doing/receiving damage, moving around) all seem to work properly.