You try to import assets without any category assigned. After the import you try to search for this asset but you won't be able to find the asset.
This is not a bug and is related to your channel configuration. The reason for this is your channel configuration: Your channel only uses categories as a base. Also if you add the asset classes as favorites, the asset won't be found if you search for it in the channel.
Please change the channel configuration to an asset class, this is a best practice suggestion.
An another workaround would be, to define a required category field for each asset class. So every newly imported Asset needs to be assigned to a category.
Please make sure, your Index is up-to-date. Please reindex your Picturepark instance, if your channel is configured with asset classes and you still can't find your asset. Please note that if you have a large amount of assets it is best to do this outside of main business hours. If in doubt please contact firstname.lastname@example.org