2.19.3 SERCOM-USART: INTFLAG.TXC being Set Incorrectly

When the USART is used in the 32-bit mode with hardware handshaking (CTS/RTS), the TXC flag may be set before transmission completes. TXC may incorrectly be set regardless of whether Data Length Enable (LENGTH.LENEN) is set to ‘0’ or ‘1’.