Last week it happened with my level 46ish group trying do the normal CoH pledge. Everyone in the group was under level 50, yet we could not enter the dungeon due to the ("your veteran level is not high enough") error. Obviously that is a bug since nobody in the group even has the option to change it since everyone is under lvl 50.
Today this happened with my lvl 20ish group trying to enter Waywrest Sewers. We got the same error message and couldn't enter. One of the group members pointed out that it was today's pledge and then it hit me - That is the connection.
In order to get into the dungeon, this is what we had to do. I had to boot one of the level 20's who then got on his V14 and joined the group. Since he was a vet character, he has the option to switch it. So he switched it to normal. Then he got back on his lowbie, I invited him to the group and we got in. However now the mobs were all V12. So we all left the dungeon and entered again and the mobs were now level 20 and we all got it.
But there is clearly a major bug here and it's clearly preventing low level groups from getting into the normal version of whatever dungeon is the pledge for that day.