Did you treat for tracheal mites?  Sounds like a CLASSIC case of tracheal mite
death; and your 2nd hive is probably very infected.
If a similar thing had happened in hot weather, then it would have been varroa
mites, but due to the laying cycle of the queen, tracheal mite death usually
occurs in January.
There is little or no treatment for tracheal mite except in warm-hot weather.
Menthol is the only tracheal mite killer approved by the government.  If
grease patties are used all 12 months of the year (even in nectar flow time),
the tracheal mite infection can be controlled but NOT KILLED.  I have always
used BOTH.           George Imirie