AD5290 Unexpected Output Voltages

Apologies if we posted this in the wrong spot. Searching for the part in question brought us to this subforum.

We sell a system with customizable I/O card configurations. We recently received some of our Output cards from our PCBA, and a good number of them fail our tests. We've narrowed down the location of the issue to a specific part of our board.

This section in question uses a DAC (AD5781ARUZ) supplied with +/-15V and with references of +/-10V through two amps (2/4 of LT6012ACS#PBF) outputting through a third amp (1/4 of LT6012ACS#PBF) into the A terminal of a digital potentiometer (AD5290YRMZ10) supplied by the same +/-15V. The B terminal is tied to ground while the W terminal is our output going simultaneously to a voltage-controlled current-source circuit and a voltage-controlled voltage-source circuit (both made with non-Analog-Devices components). Both the DAC and Potentiometer are controlled using the same digitally-isolated (non-ADI component) SPI lines from a (non-ADI) microcontroller but with different SYNC/CS lines, respectively. The concept is that we use the DAC to adjust a percent-full-scale (PFS) value and use the the Potentiometer to adjust the voltage based on what current or voltage output is desired.

The problem seems to be something to do with the gain of the potentiometer, but the strange thing is that the problem is consistent among all the bad boards. That is, the ratio between output (current or voltage) vs PFS is nearly identical (greater in all cases) on all bad boards. We have four possible configurations: +/- 40mA, 200mA, 10V, and 5V outputs. On a good board, the gain is set to 1 for +/-10V, ~0.5 for +/-5V, and a third and fourth value for the two currents. In a bad board, the potentiometer is at least somewhat functional, as the output is adjusted, albeit incorrectly, for both current outputs, but stays at a gain of 1 for both voltages (which is only a problem for one of them).

The question is, what's wrong? This seems to be an issue of semi-bad potentiometers (they respond, but not correctly). But, for multiple boards to have a nearly-identical issue would mean that whatever is wrong is the same, and the likelihood for all the potentiometers to have been damaged in the same way is incredibly low. Perhaps the issue lies elsewhere. We thought that there was a chance that chips with different resistance were installed by mistake, but according to the part markings, this is not the case. Another considered possibility is that the reference voltages on the DAC are incorrect, but this would only explain away the issues on the current output; with both voltage outputs being the same, this points back to a potentiometer issue.

In the meantime, we will continue to troubleshoot. Our next steps are to solder some test points onto our board to read the actual voltages outputting from both the DAC and Potentiometer, as well as the supply and reference voltages.

If more information is needed to help us troubleshoot this problem, let us know. We are hesitant to provide more information than necessary. I (the person actually writing this) have currently received permissions from my higher-ups to post only this information.

EDIT: Below is a schematic of the area in question.