I can’t say what is happening with your system, but here is mine in comparison. Roon Core - Auralic Aries G1 - Anthem STR Preamp. The Anthem shows whatever sampling frequency that the source (Roon) provides and indicates. So what you’re seeing it is not expected behavior.
When you say "outputting 44.1," you mean that’s what it displays on the screen? I assume you are using the STR’s own DACs, so it’s outputting analog.
My guess is a setting in either the Core machine (which has DSP including sample-rate conversion) or the Node needs adjustment.