The values of calculated columns are not stored by SharePoint but calculated on the fly when a list item is requested (e.g. from the web UI or a web service call).
SQList treats calculated columns just like other columns when it exports the list's data to the corresponding SQL table.
However, if a calculated column is added after SQList has exported the data, the new calculated column will be added to the SQL table but its data will not be populated.
The reason for this behaviour is that SQList always synchronises the structure of the SQL table with its corresponding SharePoint list but only updates the rows that have changed since the last data synchronisation.
SQList uses the "Modified" value of the list item to detect updates and adding a new calculated column will not change it (in fact, the actual data in the list have not changed).
It is not possible to force SQList to re-populate all columns and the only way to obtain that is by either deleting all rows in the SQL table (DELETE * FROM [<table_name>];) or by dropping it altogether (DROP TABLE [<table_name>];) and let SQList re-export all content from scratch.
Note that in both cases, any correlated tables (e.g. attachments, multi-lookups, etc.) must be dropped/emptied too.