Hello @Cyriactoms
I hope you are doing very well.
I noticed that in your UART3 configuration, you are mixing DCE and DTE modes for the TX/RX and RTS/CTS pins. This inconsistency can lead to improper signal routing. Please ensure that all pins for a UART instance use the same mode (either DCE or DTE).
Also, the rs485-rts-active-low property assumes your transceiver enables transmission when RTS is low, please be sure about it.
Several of your RTS/CTS pins are muxed from SD1 interface signals. Ensure that usdhc1 is disabled.
I hope this can helps to you.
Best regards,
Salas.