On page 31 of MAX14830 datasheet (document ID 19-5547; Rev 7; 2/16), it states "Note that an error can occur in the TxFIFO when a character is written into THR at the same time as the transmitter is transmitting out data via TX. In the event of this error condition, the result is that a character will not be transmitted"
This is untrue. The newest silicon revision (REVID changed from 0XB3 to 0XB4) fixed this issue, but this info was never removed from the datasheet