I was suggesting you to use lower baud rate, not higher. You can do this by increasing the divider in your SPI INIT function:
SPI1_Init_Advanced(_SPI_MASTER, _SPI_8_BIT, _SPI_PRESCALE_SEC_1, _SPI_PRESCALE_PRI_16,
_SPI_SS_DISABLE, _SPI_DATA_SAMPLE_MIDDLE, _SPI_CLK_IDLE_LOW, _SPI_IDLE_2_ACTIVE);
...instead of the original SPI_Init which contains _SPI_PRESCALE_PRI_4
, dividing the SPI clock with 4. You can try even bigger values for the divider (64), experiment a bit with the primary and secondary prescale as the SPI tends to be sensitive to long signal paths, poorly designed paths, so if it's too fast it might simply fail. After all I told you that I can't guarantee you it will work, since the library doesn't include that MCU by default - so it's either not supported fully, or it's not tested. I will ask our developers to look into that, but in the meanwhile, we should try out few different settings for the SPI and see if that helps.
Finally - do you use a custom made PCB, or you some factory-made product with the dsPIC33EP ? If so - which one ? When I was speaking about routing the SPI lines, I was talking about physical paths of the SPI signals - I wanted to make sure that the ENC chip is properly connected to the MCU's SPI pins, in case you were making your own PCB. Also if you did your own PCB, I'd like to take a look at the schematics, if possible...
I hope some of this will work for you, looking forward to your answer,