Problem with your schematic: The pins which TXLED# and RXLED# are on are tied internally to VCCIO with 200k resistors. The LEDs themselves are connected to VCC. Because of this, connecting voltages lower than 3.3V such as 1.8V or 2.8V to VCCIO will not work as they are supposed to because VCCIO is being pulled up to 3V+. So for this schematic it is not possible to have less than 3.3V on TX and RX as they’re being pulled up to VCC (minus diode drop).
For anyone wanting 1.8V or 2.8V on VCCIO, to get around this R1 & R2 can be removed (meaning you lose the LEDs) or they can be removed from the pad connecting them to VCC and jumped to VCCIO.