Pin assignment for UART on the nRF54L15DK

[a.da]

Hello.

I am testing UART connectivity using the nRF54L15DK.

After assigning pins to TX and RX, there were combinations that worked fine and combinations that didn't.
There are no build errors. The program starts up successfully, but UART communication doesn't work.
In both cases, there doesn't appear to be any conflict with other pins.
Even after explicitly removing "uart30_default" and "uart30_sleep" where P0.0 and P0.1 are used, the results didn't change.
Since RST and CST are not being used, I haven't assigned them.

The "nrf54l15dk_nrf54l15_cpuapp.overlay" is as follows. Everything is the same except for this file.
Is there any configuration oversight or constraint?

OK

/ {
	chosen {
		nordic,nus-uart = &uart21;
	};
};

&uart21 {
	status = "okay";
	current-speed = <9600>;
	pinctrl-0 = <&uart21_default_alt>;
	pinctrl-1 = <&uart21_sleep_alt>;
	pinctrl-names = "default", "sleep";
	/delete-property/ endtx-stoptx-supported;
	/delete-property/ frame-timeout-supported;
};

&pinctrl {
	uart21_default_alt: uart21_default_alt {
		group1 {
			psels = <NRF_PSEL(UART_TX, 1, 11)>, <NRF_PSEL(UART_RX, 1, 12)>;
		};
	};
	uart21_sleep_alt: uart21_sleep_alt {
		group1 {
			psels = <NRF_PSEL(UART_TX, 1, 11)>, <NRF_PSEL(UART_RX, 1, 12)>;
			low-power-enable;
		};
	};
};

NG

/ {
	chosen {
		nordic,nus-uart = &uart30;
	};
};

&uart30 {
	status = "okay";
	current-speed = <9600>;
	pinctrl-0 = <&uart30_default_alt>;
	pinctrl-1 = <&uart30_sleep_alt>;
	pinctrl-names = "default", "sleep";
	/delete-property/ endtx-stoptx-supported;
	/delete-property/ frame-timeout-supported;
};

&pinctrl {
	/delete-node/ uart30_default;
	/delete-node/ uart30_sleep;
	uart30_default_alt: uart30_default_alt {
		group1 {
			psels = <NRF_PSEL(UART_TX, 0, 0)>, <NRF_PSEL(UART_RX, 0, 1)>;
		};
	};
	uart30_sleep_alt: uart30_sleep_alt {
		group1 {
			psels = <NRF_PSEL(UART_TX, 0, 0)>, <NRF_PSEL(UART_RX, 0, 1)>;
			low-power-enable;
		};
	};
};

Thanks for reading.

a.da