Mireu

Please limit the number of players available in this content/fight, and reduce the NM's hp accordingly to said limit. The issue is simple, too many players, too much lag, not everyone can even see the mob especially if arriving late to the fight, yet alone even target the thing. Thanks~!

I wish they could prioritise the visibility of Mireu over (non-party) player characters (similar to what seems to happen in Besieged).

To somewhat work around this particular issue, I usually get Mireu to become visible almost always if I run away far enough outside of the battle area for player chracters to disappear, then run back. Of course this isn't that doable in Reisenjima, and might be tricky in Escha — Ru'Aun, but at least in Escha — Zi'Tah it seems to work pretty well.

Try running out of range of mireu, maybe just a little further than being able to see other players around it. Then run back in. I tried it the last 2 times I've seen him and it worked. Hope it works for you as well!

Don't forget to turn off all other players' trusts.
/hidefaith on or /hidetrust on both help with that iirc.