J-BusinessDirectory - Imported listings not showing on map

Most of my imported listings are not showing on the map. In the backend, the address data seems to be imported correctly, although the field "Business location" is empty and the map below is blank.

I thought that the map function would automatically locate the listings on the map?

example of import file:

website;name;categories;address;postal_code;city;phone;email;type;country;package;approved
www.schauaquarium-nautiland.de/;Meeresaquarium Exotarium Nautiland;Aquarien;Marktplatz 2;06463;Sonneberg;03675427888;info@schauaquarium-nautiland.de;Freizeitaktivitäten;Deutschland;Kostenlos;2
;Tropen-Aquarium Hagenbeck;Aquarien;Lokstedter Grenzstr. 2;22527;Hamburg;040530033-0;;Freizeitaktivitäten;Deutschland;Kostenlos;2
www.aquarium-geomar.de;Aquarium - Institut für Meereskunde;Aquarien;Düsternbrooker Weg 20;24105;Kiel;02323946280;info@aquarium-geomar.de;Freizeitaktivitäten;Deutschland;Kostenlos;2

I guess website is not imported because those listings will have free package assigned which does not include a link to the business website, right?
But what about the other issue, why is the address not used for Google maps?

Also, I have noticed that a lot of listings were created two or even three times.

Hi,

When a listing is being imported the map coordinates are resolved based on the postal code.
For that, you need to enter the map key on general settings and also do a zip code search on front-end to make sure that the postal code is translated correctly.
For zip code translation we use google services and there is a limitation on the number of items that can be performed. You can check the google map api page for more details. 

I see. I just activated billing to increase my number of requests for the APIs. I guess that I have to delete all listings and re-import them again, right? Should I only import a certain number of listings in one go to make sure the process runs smoothly, and what would that number be?

But what about all those duplicates? I had app. 8000 data sets but over 13.000 listings were created. How do I avoid that for the next import?

Just tried to re-import with files containing 1000 sets of data. First file imported, only app. 400 data sets were created. Looks like I have to split the files to smaller sizes

strange, after the finishing of the import process, I still get that error screen, and after I go back to the admin (overview) only 400 listings have been created out of 1000. BUT it seems that the creating process is ongoing because the number of listings keeps increasing. Looks like after every batch of importing, I have to wait a few minutes for the process to finish before importing the next batch.

So after the third run op importing the data, it works as long as I do batches of 1000, which take app. 10 minutes to process. Had to edit the csv files because spaces in the postal_code field have undesired effects.
But there still seems to be a problem with the map view - on the homepage, lots of listings are shown on the map for the Northern parts of Germany, but practically none in the southern part although plenty listings have definitely been created in that area.

Strangely, the listings show when I do a radius search with a zip code from the south (on the map that appears after the search), but not on the home (which makes it look like I only have listings in the north).

importing all 8000 definitely does not work, although I have uploaded a php.ini with max_execution_time=12000 to the server, both in the root and in the component directory. I still get an error message and then there are only app. 600 listings created.

after cleaning up the cache and setting the map module to max 1000 listings, now icons are showing all across the map but there are many, you cannot see the map anymore at all now lol. Could it be the system shows only the first 250 listings created on the map? Is there a way to show, for example, all listings from a specific category in the default homepage view?

Hi. 

The map currently displays a number of listings that is limited by the Joomla pagination settings. 
You can show listings that are specific to a category by creating a menu item of type Business Listings and filtering by a category.