Why won't my toilet hold the refill water?
Nothing has changed, your toilet still drains too slowly, you still need to clear the obstruction. The bowl completely clearing will sometimes happen with partially obstructed toilets because, due to the very restricted passage, the vent air that normally breaks the siphon action cannot make its way to the bowl until long after all the tank water has been completely drained into the bowl, leaving no fresh water to refill the bowl.

As soon as the passage is cleared to its normal size, the vent air will have room to work towards the bowl and quickly break the siphon. The bowl is then refilled with the remaining fresh water, ready for another flush cycle.

ADDENDUM

Depending on the nature of the obstruction, if it's difficult to completely clear with an auger, and assuming the toilet bolts are not too badly corroded, it's worth removing the toilet and working at the obstruction from both ends. It's usually easier than most people think. There is still a portion of the passage that is difficult to reach, but you've doubled your chances. For the typical floor mounted residential toilet you will at least need a fresh wax ring to reinstall the toilet.