Hey man. I know you're pain firsthand. Since launch I've been playing with two friends & we've never had issues with summoning one another for a total of three players (host + two summons). Last night we decide try summoning a fourth friend using the dried finger. Initially we could get the host + two scenario but as soon as the finger was cracked we were getting invaded like mad & no new summon signs. When one of the party died, the host could immediately see the summon sign of the fourth person who had been trying for a summons.

Here's where it gets shitty.. In an effort to make this work we all change our network settings to what's listed above (Previous we had all on No matchmaking, 3 letter password, restricted visibility.) & suddenly we're experiencing what you stated is happening. Each of us can now only summon one player. We tried for well over two hours last night. When it was my turn to try hosting, before I summoned anyone I could see all three signs clearly. I pick one & the other two would immediately vanish. Eventually we found that using the dried finger would allow for summoning a second person in but that started to the flood of invaders. When I say flood, I mean it. Literally two at time. We kill one & I another invader within 20 seconds took their place. I like pvp as much as the next guy but that made venturing anywhere impossible. They should really consider changing the way the dried finger functions to allow only one invader until you have 4 players, then increase it to 2. I'm seriously hoping this resolves itself when we go to play tonight as last night we were on for 3.5 hours total & made no headway I whatsoever until we all gave up on trying to summon & pressed forward solo.