When using variable length packet mode and address filtering, the Length byte sent must be increased by one. Failure to do this results in the last payload byte not being transmitted, and the library, ...
MOSI/SI (#6) GPIO7 Pico → CC1101 SPI serial input MISO/SO (#7) GPIO4 CC1101 → Pico SPI serial output GDO2 (#8) GPIO3 CC1101 → Pico Demodulator output ...