It seems the Airspy Mini bias tee might be able to handle the current demands even though it is only rated for 50mA - see this thread - Airspy and bias tee
I can’t comment from personal experience as I use an Uputronics LNA/Filter that is powered from a separate USB port on the my Raspi 4 with my Airspy Mini.
lsusb output for the mini is the same as the R2:
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 003: ID 1d50:60a1 OpenMoko, Inc. Airspy
Bus 001 Device 002: ID 2109:3431 VIA Labs, Inc. Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Dumb question, but have you got the triple filter connected the right way around? 
I have a vague memory of another thread where someone confused the signal path direction of the in and out labels - in is from the antenna.