OK so it looks like this is impacting the chain if you are doing decoding or full hardware rendering on the DAC itself. (My Gustard X16 does this but I’m circumventing it since I am using HQ Player to upsample, I have Roon do the first unfold (decode only) and HQP take its from there). In your case I would switch back to the Low Latency Filter and add the Procedural EQ to boost the volume.
@KMan can hopefully shed some light on the technical aspects of why this may be happening to the Linear filter. Here is a link to the support thread with more details.