Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/STMicroelectronics/STM32F7x8/OTG_HS_DEVICE/OTG_HS_DIEPTSIZ0#0x0
OTG_HS device IN endpoint 0 transfer size register
Transfer size
Packet count
https://github.com/cmsis-svd/cmsis-svd-data