All servers are back online after the Game Update 61 patch. This update introduced a massive item overhaul and changes to the Alternate Advancement system, some of which has caused issues now that it has gone live. Here are some known issues:

• AAs are not reset. Zoning once will fix this.
• AAs reset themselves after leveling. No user-side fix for this
• AAs reset after reassigned if you zone. Zoning at least once before reassigning them should prevent this.
• AAs are resetting for some people upon logout. No user-side fix for this.
• Items that may have previously had stats beneficial to your class no longer do. The best thing to do for this is to /bug report the item and explain which stat is missing from it. Double check any unattuned item before re-equipping it!
• Items may be assigned to the wrong slot. These are few and far between, but /bug report them as you come across them.

Zoltaroth gave this warning regarding AAs:

We found some issues with the AAs resetting.  We will likely do another full reset with the next hotfix.  Just posting here as a heads up.

Rothgar later added (regarding item attunement issues):

We will be hotifixing this bug tomorrow.  The downside is that all of your items will become unattuned again and we will refund adornments applied to any equipped gear. 

After this runs tomorrow, the items should remain unattuned until you decide to attune them again.

Tomorrow's hotfix will also include a fix for the AA trees not resetting properly or resetting at incorrect times.