Received ERROR while using XCVR_TX_COMMON_MODE_VOLTAGE for Arria5 GX Transceiver

Using Documentation Link:

https://www.intel.com/content/www/us/en/docs/programmable/683084/current/xcvr-tx-common-mode-voltage.html

Says I should be able to set this in the QSF file with a set_instance_assignment. The device I am using is:

5AGXFB3H4F35C4

Quartus Version: 21.1.0.842 on Linux

Command example in my QSF file:

Error from Quartus when processing:

This error occurs during FIT so the QSF parser thought the command was OK. I did try a value found for the XCVR_RX_COMMON_MODE_VOLTAGE which was VTT_0P35V and the QSF parser said it was illegal.

So the question is? Can I make this assignment? And if so what are the legal accepted values by the Fitter for the device I am using? I am using a custom data rate and protocol so please don't ask me to choose one of the existing profiles -- they will not work in this situation. Also I cannot upload the design -- the best you get is screen shots like above; company policy ;-(