Op amp unity gain too low
Your schematic shows the op-amps being powered from a 3.3V supply. The most you'll get at the op-amp outputs is 0 to 3.3V. (Even the data sheet confirms this on line 3 of the features list - "Rail-to-Rail Swing at Output").

With the op-amp configured as a unity gain block this means that the input cannot range outside of 0 to 3.3V.

If you try to drive the inputs above the power supply level you may damage the parts. In the same data sheet they specify that the maximum rated input is at VDD + 0.3V. That is not a recommended operating condition but one above which you could cause serious damage to the op-amp.

It is possible that the internal design of the op-amp is such that inputs above the supply rail may try to act as a power source for the circuit and cause the outputs to do strange things. This could include clamping to a lower level output or to rise above VDD as well.