Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Microchip Technology/ATSAMV71J20/USART0/US_IDTRX#0x0
LON IDT Rx Register
LON Indeterminate Time after Reception (comm_type = 1 mode only)
https://github.com/cmsis-svd/cmsis-svd-data