ELV RX868-3V Question for the experts: FSK Modulation Problem

I have a question:

When I analyze the original transmitter and receiver, I can clearly see the transmission (12ms; about 200 bits; 58us H; 58us L). the signal is clear and decodable. Same with HDSDR, clear to see!

With all three RX868 receivers ( no i2c/SPI only DATA_OUT) only a rectangle of 12ms!

D0: RX868 Signal (12ms H)
D2: org. Send unit
D3: org. Receiver unit

Am I doing something wrong?

ELV Empfangsmodul RX868SH-DV, 868,35 MHz | ELV Elektronik | Bauteile / Komponenten | ELV Elektronik

Are the older modules (no SPI) not capable of FSK?

Library needs to support it