Reproduction:
User creates premade with min iLv. User then invites friend who has a lower iLv. Raid shows up in oQ with the lower person's iLv resulting in someone seeing the raid (when using the "Qualified" filter) and is unable to join because "Not Qualified".
This also appears to cause oQ to not bother filtering raids that are looking for specific classes/roles. I've had several that I actually met the iLv for, but because of the iLv display issue it shows the raid to me when I'm DPS and all they want is Tank or Healer.
Visual:
When mousing over the raid, it shows the Req iLv, then shows the actual lowest iLv which matches what the filter is triggering off of. People asking for iLv 570+ for Flex 4 and have a guildie/friend at 496 that they're carrying for the BoA causes the raid to show in oQ as 496 Minimum with all roles being looked for. When attempting to join you'll get a "Not Qualified" (if you're not actually high enough iLv for their true min) or the 'incorrect role' (can't remember the specific text of the error) if you're not one of the roles/classes they want.