I used a Blue Eye Stone at the beginning of the Tower of Latria level and was summoned, but the player I was helping died before we got to the boss. I was sent back to my own world, went back to the beginning of the level and tried to put down another sign with the Stone but I couldn't. (the option to use the stone was grayed out)
I went back to the Nexus and then back to the level to see if that would help but it didn't. I eventually was able to put down another sign with the stone and got summoned again but I invaded their world as a Black Phantom. I retturned to my own world using the White Eye Stone. I did it again and was summoned but invaded as a Black Phantom again. I am 100% sure I used the Blue Eye Stone and not the Black one because I saw the summons message on the ground and made sure to examine it when I put it down the second time.
I thought about just going through with it and killing the player I invaded but (a) I do not want to move my world to Black tendency, and (b) thought it would suck if I had tried to summon a Blue Phantom to help me but got invaded by a Black Phantom who tried to come and kill me instead.
When you put down a summon sign in the Tower of Latria there is a chance you'll get summoned to be the Black Phantom for the boss fight. There is nothing you can do - the servers decide if you're going to help someone as a blue, or if you get chosen to be the Black Phantom.
If you're summoned as a Black Phantom you can exit out if you want, you can put up a minimal fight to allow the host player to win the boss fight, or you can really fight and make it a challenge for the host. It's up to you.
So is this a glitch? Because everything I have read on here and other sites and the manual's brief section on stones (I have the digital download version) says nothing about ever being summoned as a Black Phantom if you use the blue Eye Stone.
This isn't a glitch. The blue eye stone gives you the oppertunity to be summoned as a blue phantom in any world. If you use a blue eye stone in worlds 1, 2, 4, or 5 you will ALWAYS become a blue phantom when you join another player. If you use a blue eye stone in world 3, you might be summoned as an invader as stated above or you might help as a blue phantom.
Spoiler and more detailed explanation below:
The 3-3 boss can be a human player. If you use a blue eye stone and another player is in 3-3 and needs a real human to fight as a boss, you will probably be summoned as a black phantom in their world. If noone needs a human boss in 3-3, then your blue eye stone will allow you to be blue phantom.
So this is not a glitch you are experiencing. Blue eye stones behave differently in world 3 than they do in all other worlds.