Sysupgrade Invalid image contents do not match checksum-Openwrt-19.07.3-ath79-generic-ubnt_routerstation-pro-squashfs-sysupgrade.bin

Trying sysupgrade on a UBNT RSpro from Lede 17.01.1 to OpenWRT 19.07.3, sysupgrade says invalid image contents do not match checksum.

The sha256sum matches downloads.openwrt.org:

from https://downloads.openwrt.org/releases/19.07.3/targets/ath79/generic/
ubnt_routerstation-pro-squashfs-sysupgrade.bin	7e384968c70cb9d484390a3e70ffcd11f9a32c62029fa0f99525167dc2345837	4160.3 KB	Sun May 17 11:22:58 2020
# sha256sum openwrt-19.07.3-ath79-generic-ubnt_routerstation-pro-squashfs-sysupgrade.bin
7e384968c70cb9d484390a3e70ffcd11f9a32c62029fa0f99525167dc2345837  openwrt-19.07.3-ath79-generic-ubnt_routerstation-pro-squashfs-sysupgrade.bin

# sysupgrade -n openwrt-19.07.3-ath79-generic-ubnt_routerstation-pro-squashfs-sysupgrade.bin
Invalid image. Contents do not match checksum (image:d51cf1fc14036c2488b80cfbf171b625 calculated:ec1e0865b44ca4dcec1152a7eb896e38)
Image check 'platform_check_image' failed.

Is this a known issue?

Is it safe to force sysupgrade to install this image?

Also, there doesn't seem to be a snapshot sysupgrade build for this device. There is only a factory image.

Thanks for your help.