Have you disabled any volume or tone controls in the Node setup?
You need that Node to do the decode without any other changes to the signal, and then it should pass the decoded MQA output to the DSPs to render, which will then show OFs in the display.
I have a Powernode but that doesn't have the same settings. I used an Aries Mini before and with the decode done in Roon and when passed through the Aries untouched it worked OK on DSP5200.2s, showing OFs. Using a Meridian 210 over MHR it shows MQA.
[I think passing it through the 800 might be a red herring, although I don't know what that might actually do.]
S