CoE Write Discrepancy PLC --> I/O

I have a device on EtherCAT and I am writing to some dictionary objects using the cyclic I/O data. The I/O data includes structures for read and write requests and well as responses. I am experiencing a weird error where I write an index and subindex, but it fails and the subindex is not mirrored back in the response. I have checked everything and there is no obvious reason for this. If I check the CoE tab of the device in ctrlX I/O Engineering, I verify that the subindex value is being written. However, the response does not mirror it back. If I initiate the command direct from the ECAT master (in the CoE tab in ctrlX I/O Engineering), it works no problem.

In PLC Engineering, the DataLayerNode I/O data

In I/O Engineering, CoE of device

The data appears to transfer from the PLC app across the datalayer to the ECAT master correctly. Yet, the command errors. Again, to clarify, if I instead clear the command in the PLC and just enter the data direct in ctrlX I/O Engineering CoE for the device, it works no problem.

CORE X3 at v1.20