Problem:

The customer was using the "save_post" hook to automatically fill lat/lon coordinates from a Toolset address type field into another custom field, but the values were not becoming available for new posts.

Solution:

Suggested to get the values from superglobal "$_POST", instead of the custom fields table.
( ref: https://toolset.com/forums/topic/extracting-longitude-latitude-from-maps-field/#post-2257137 )

Relevant Documentation:
n/a