Possibility for UART receive data loss?
H/W flow control between UART's RTS/CTS with 16 byte Rx buffers are intended to prevent overflow. But it useful to include parity to improve signal integrity in case flow control latency is too long.  

When demanding low error rates with software retry or data filtering or testing max data rates in noisy environments, it is useful to enable parity.

It is also beneficial to check for ; stop bit errors, buffer overflow errors and test with simulated environmental noise.  (ESD, RF pulses  , SMPS CM noise etc. lack of earth grounds etc. )