When playing Tidemistress Athissa with Warlord Parjesh 1 equiped no naga is summoned.
I would post a link to a screenshot of the start of a battle where no naga has been summoned but i am not allowed to post links.
Are you sure you’ve equipped the right piece for the party that you’ve gone with to that particular fight? Equipment is party-specific, which is a feature, however, we’ve got plenty of people who either have missed it or can’t/don’t like to read (patch notes in particular), apparently, reporting such ‘bugs’ regularly; what I asked about tends to be the most common cause of their problems.
I was having the same issue. To provide an actual answer to your question : I have Warlord Parjesh at level 2. So I made a party with only two members (Athissa and one other) and he spawned just fine. I don’t think he will spawn with parties larger than his level. I hope this clears things up. I’m guessing that if you upgrade him you can use him with larger parties.