I recall others reporting issues trying to run Crossfire on UART3 on this board, regardless of the solder jumper position. It looks like this board has an inverter on UART 3, so you could also try disabling it with:
The only other thing I notice is that UART1 has DMA resources assigned, while UART3 does not. In the Ardupilot world DMA is required for CRSF, but I haven't seen (lack of) DMA resources cause any issues with CRSF on Betaflight.

It did not help but soldered to uart1 and works well.

Hello, folks. I've just gotten the same problem with this FC. I was about to discard the pin connector and solder the TBS Nano Rx to the UART1 when I though on doing a little more tests.

I used a multimeter and I found that on those three pads where you choose between DSM and SBUS, although I soldered the DSM and the center pads as needed for CRSF, there was conductivity between the center pad and the SBUS pad. There was a very tiny soldering thread there, almost invisible for the human eye (at least for mine, lol). So I desoldered it and cleaned it very carefully, making sure that there was no conductivity between center and SBUS pads, but only between center and DSM pads.

And that was it, it worked fine, the FC recognized the receiver and I could see the bars moving in he "Receiver" tab in Betafligth.

I hope this helps somebody.

Have a nice day.

Giovany Arana
IG: https://www.instagram.com/garanal78/