The WPSLP Power Add On or MySLP/Professional plan allows you to import CSV files with several options. View the information under SLP/Locations/Import . You have various options to consider when determining how to update locations that match your pre-existing locations.
Options available on how to handle duplicates: Choose to Add, Skip, and /or Update.
WPSLP 4.9.x or above Power add-on uses the built-in file up-loader provided by WordPress Core instead of a custom file import script. If you were able to import and now do not see that process working, look in the Media Library in WordPress. Make sure your install has not disabled the default WordPress media up-loader.
NOTE: As of July 2018, if you are using the WPSLP “do it yourself” plugin with Power add-on and you have not included the latitude and longitude and require geocoding , make sure you have a Google API account and have checked off the Maps and Geocoding APIs in your library.
What to look for when importing
Do you see the CSV file you just imported? If not then your site has disabled the WordPress media uploader.
If your file IS in the media library but never gets past the offset “0” setting check to make sure your server has not disabled the WordPress Cron .
Check to see if your server is preventing the wp-cron.php from being triggered.
Check your import file in the media library by clicking on it. It should show what the file size is and the current offset. The offset is where the background process is shown while importing the file. If it is shown as “zero” then your WordPress Uploads directory for the media library has been set to non-standard restricted access meaning the background location import process is not allowed to open the file after it was uploaded.