I connected JLink using the pads on the back of the board.
After erasing the chip, I uploaded ”blink.ino.with_bootloader.hex” and confirmed that it blinked without any problems.
I checked the SecureElementStatus with SymplicityCommander, and it was the same as the screenshot posted by @grobasoz.
However, I couldn’t upload from USB, and I got the message “Error: Error connecting DP: cannot read IDR.”
The message suggests that the MG24 is refusing to connect to the DP. Alternatively, there may be an issue with the SAMD11 between the USB and the MG24.