After further attempts I am almost at the same place

I think that maybe I do not understand some basics regarding using RFM69HW.
Currently I have connected RFM modules to separate NUCLEO boards with STM32, but the problem is similar. The transmitting module transmits, but the RSSI measurement takes from a few dozen to a few hundred milliseconds (randomly, i mean waiting for
RSSIReady bit), after which the read value fluctuates around -100dB, which does not meet the threshold condition of the
CSMA_LIMIT level (-90dB). Finally, the module transmits data (view on SDR) thanks to exceeding the timeout for the RSSI measurement (yes, I set such a timeout for the start-up time). Regardless, the receiving module does not receive the frame (it does not set the
PayloadReady bit). The modules have the same configuration (except that I turn one into receive mode), I do not use address filtering, they are connected to NUCLEO on cables of about 20cm, and there is a 100uF capacitor on the power supply at the RFM module. SPI works at 1MHz and the frames look correct (I tried 250kHz, and 2MHz and 4MHz according to the recommendations - no difference). I tried moving them a dozen or so meters apart - no difference.
Please help, because I feel like I'm making a mistake somewhere at the basic level and I don't see it.