Significant error with unity-gain feedback op-amp
Figure 1. From the datasheet.
Note that when running on a ±15 V supply that the inputs can be taken to within 1 or 1.5 V of the supply rails.
If that deviation remains constant at ±4 V then you could expect the inputs to work in the range ±2.5 V to ±3 V. I can't see where you could work that out from the data sheet.