Plants remain unidentifiable [Granite Falls]

This is not a game bug. Please see CGrant56 reply below:

The unidentified plants in Granite Falls always remain unidentified.  The only place they go from unidentified to identified with their correct names is in your sim's inventory once you've identified.  Otherwise, only one sim in a household could complete the OR aspiration milestone to identify the 10 Herbalism plants.  And, once you identify one, if you go back and collect it again while you have identified it, then you have both identified and unidentified harvestables in the same stack so you'll have to find the unidentified ones and identify them again before you can use them to make the remedies.  It's designed to work that way and is not a bug.