Unable to target party members in dungeons/instances

Time: Most recently 9:17pm Central
Frequency:8 out of 10 times I run a dungeon
World name: Leviathan
Character name: Neverhood Redmane
NPC name: N/A
Monster name: N/A
Class/Level: 36
Party or solo: Party
Area and coordinates: Sunken Temple of Qarn (most recently, but happens in all dungeons)
Steps:
No particular steps are taken. More often than not, when running a dungeon a member of my party will suddenly stop moving on my screen. They are still gathering emnity and animating as if they were traveling....but the character is displayed as still. The problem is that I cannot target them for healing unless I stand next to the actual image of the character on my screen, when in reality they are half way across the dungeon. Emnity lines are drawn across the map. The only way this issue fixes itself is if the person in question dies and respawns. I've never seen this issue fix itself otherwise.
One thing to note, it happens far more often during peak times rather than off peak.

Connection Specs
- AT&T Uverse Fiberoptic

Model Number of the PlayStation 3 You Are Using
Launch Day model

I'm playing on a PS3 thus I cannot capture video of this happening. But I'm happy to assist in any way possible moving forward with this issue. It has been happening since launch.