Guild Puzzle
Make sure you are repping the guild that you want to run the mission in. Then head to the guild mission panel and see if you have a guild puzzle available in your mission selections.
If you have it you will only be able to do that mission. Click the activate button and head to where you need to go. Once there you should be able to talk to the flag and get a box with a drop down menu. Select your guild from that list and then enter the instance.
Hope that helps.
IGN: Soren the Always Lost
Gaiscioch Family [GSCH]
Gaiscioch Family [GSCH]
I think you need to update the guild privileges in your guild, and check whether the rank of guild leader has the authorization to “activate guild missions”.