Ive got an ARZIR720fb with 11's plus a 70 for the 7th string in Drop A.

My high e has pretty bad intonation past the 12th fret but Ive tightened it all the way but it still falls flat and theres no more room to adjust it.
What other issues could this be or is a set up needed?

And IF a guitar is perfectly intonation should every note when fretted be exactly in tune? or will some be slightly out?
I think this is one of those things you gotta ask a guitar tech about.. but from doing a bit of looking around websites, one of them mentions to:

compare the pitch of your 12th fret harmonic to just playing the 12th fret's note. 
- If the fretted note is sharp, the string needs to be lengthened.
- If the fretted note is flat, the string needs to be shortened.

I dunno how your guitar is like, but usually you can lengthen/shorten the string with the bridge

Disclaimer: this info was found off of 10mins of research, I'm by no means a guitar tech.
- Strandberg OS 7
- A cheap fender strat knock-off not worth naming
- Garageband
- Boss GT-1
- Potato
Sorry forgot to add I've done the 12th fret harmonic and fret note, they are both in pitch. but anything past the starts to fall flat. The 24th fret is way flat, thats supposed to be in pitch as well correct?
Usually when the intonation is set at the 12th, anything past the 12th fret gets progressively more and more sharp as the string height increases towards the 24th fret.

What this may somewhat suggest is that the nut action of your guitar is super high. because a really high nut will cause the first few frets to be very sharp and progressively get less and less sharp the closer to the 12th fret you get.
Quote by Axelfox

Quote by H4T3BR33D3R
I also have to do that. Cottaging this weekend