I guess this same bug seems to be getting worse. I reported the whole thing THREE WEEKS ago the first time.
Please make your own bug report. I hope Funcom manages to do something if there are enough bug reports.
This bug appears to be related to altitude. If you are high enough, thralls get stuck, dont follow, and wont teleport to you if you move far enough away. Additionally none of the rituals in sorcery benches work (grave, circle of power, transportory stone). So far the plateaus around the volcano (one step higher than the temple of frost plain) seems to be the limit.
This bug has basically made it impossible for me to continue playing normally as my main base is in the volcano area. Its been like this for THREE WEEKS.