Check the curvature of the neck.
After tuning accurately, hold the guitar in playing position.
Use Capo on the first fret. Press down at the fret that is nearest to the point where the neck joins the body, and measure the gap between the string and fret at the eighth fret In the same way, measure this gap for the lowest string, and make adjustments so that the gaps are in the range of 0.3 mm--0.5 mm.
Using .38mm.
The following video says 7th fret. But above is from Ibanez so use 8th fret.
If String is touching fret OR Feeler Gauge is touching then truss rod is to tight,
we need to Loosen Truss Rod.
Counter Clockwise Motion (If viewing from top of bass guitar)
Down
https://www.youtube.com/watch?v=c2DlwxSIPA0
Take kapo off,
Use 6 inch scale Metal Ruler.
Find fret where neck joins the body,
E string should 4/32 above fret,
Rest bottom of bottom ruler on top of metal fret.
From bottom of E string NOT center of string.
Adjust saddle Screws Clock wise (looking down at bass ) to raise saddle. Adjust both screw together to keep level.
G String should be 3/32
A and D should be between 3/32 and 4/32
Ibanez Manuals says 2 MM for E String 2.5 mm for G string
4/32 is 3.18 mm
3/32 is 2.38 mm
Basically it seems Ibanez action can be a little lower.
I am sticking with video.
https://www.youtube.com/watch?v=cI9Y9MsmnEc
Feeler Guage .022 or .55mm on 1st fret
To Fix this we need to File down at the Nut.
All of my strings are a Little high but for the most part very close so not bothering.
D string is the worst. I have no doubt D could use a file. It is higher than the G String.
For now skipping.
https://www.youtube.com/watch?v=FC30nJgIAJM
Here we play Open note and 12 Fret Note. Both need to be E on E String.
If 12th Fret E is OFF we need to adjust string length using screw driver at bottom of saddle.
Do for each string.