Aliaromus passive skill "tyrant's pack" bug

The skill "Tyrant's Pack" of Aliaromus is described as usable in solo play, but when I am not in a party, the skill does not work.

I discovered this while playing because my status bar did not display the buff increase from that skill.

I believe this skill should be effective when played solo and should display its buff effect above the health bar, just like other skills.