I’ve had similar issues with my JL Audio subs not coming on as soon as I would like.
I know, different subs different animal, but the aggravation is the same. Not enough LF to wake em up and if your playing something with little to no LF they go back to sleep after about 30 minutes.
JL Audio support advised to use standby to prolong the life of the subs and use both left and right inputs to double the gain being received. That works if it doesn’t double up on hum.
Another option is the turn the volume on the sub down slightly and increase the signal from the source, room correction in my case went from - 3 to +3 db.
I found an album from a Roon search called BASS TEST. Playing that will definitely wake up the subs. I use it to verify everything is working properly.