Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Microchip Technology/ATSAME51J19A/USB/DEVICE/DEVICE_ENDPOINT[4]/EPINTFLAG#0x0
DEVICE_ENDPOINT End Point Interrupt Flag
Transfer Complete 0
Transfer Complete 1
Error Flow 0
Error Flow 1
Received Setup
Stall 0 In/out
Stall 1 In/out
https://github.com/cmsis-svd/cmsis-svd-data