Mlnx_qos set dcbx to firmware gives error, mlnx_qos PFC setting not persistent

I am using mlnx_qos 1.2 with connect x6.
My OS is ubuntu 20.04.1
NVIDIA-SMI 555.42.02, Driver Version: 555.42.02, CUDA Version: 12.5
mft 4.25.0-62

When I try to run sudo mlnx_qos -i cx6_0 --dcbx=fw, I get the following error.

Traceback (most recent call last):
File “/usr/bin/mlnx_qos”, line 396, in
File “/usr/share/mlnx-tools/python/”, line 204, in set_dcbx
self.check_err(m, DCB_ATTR_DCBX)
File “/usr/share/mlnx-tools/python/”, line 164, in check_err
raise err
OSError: Netlink error: Bad value. see dmesg.

I am trying to do this because for some reason, after setting sudo mlnx_qos -i cx6_0 --pfc 1,1,1,1,1,1,1,1 and seeing that the PFC is enabled, after about 20seconds or so, running sudo mlnx_qos -i cx6_0 and I see PFC is disabled for all priorities. I was thinking maybe dcbx is messing with the setting so I tried making dcbx managed by firmware.
Any help with solving these problems would be appreciated.