Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Keil/AT32F423xx_v2/USB_OTGFS_DEVICE/DIEPTSIZ5#0x0
OTG device IN endpoint-5 transfer size register
Transfer size
Packet count
Multi count
https://github.com/cmsis-svd/cmsis-svd-data