This older bug is related to having the Ring of Entanglement equipped to companion(s) who are inside the endgame fathoms.
As a workaround, load an earlier save file and remove the Ring of Entanglement from your companions and the Last Castoff, as that may resolve the issue.
Please note: This issue was resolved with the 1.1.0 patch, though you may still need to load an earlier save file to benefit from the fix.