sorry, i did miss the R1 vs A3 and that your device seems still in heavy development.
R1 seems only mentioned here a bit: DLink DIR-853 A3. That thread mentions at the end that the A3 master images were broken the recent days - maybe this also applies for your R1. I would keep an eye on that thread to stay up to date with development.
Overall your R1 seems to be the friendlier variant since it has the recovery boot loader by default, so unlimited retry attempts for you without bricking it.
You might also try flashing newer snapshots again in a few weeks, once built images are sane again. Or ask in the other thread, if A3 and R1 images are still known to be broken.