imported data not refreshshing in visuals

Hello vickster3659,

The 12th CSV was likely imported successfully, but not added to the final appended query used by the visuals.

Check the following:

• Confirm the 12th file contains rows in Power Query.
• Verify the Append step includes the new file/query.
• Ensure column names and data types match the previous files.
• Select Close & Apply to refresh the model.
• Check for filters or slicers excluding the new month.

For future monthly files, using Folder import is usually easier and more scalable than manually appending CSVs each month in Microsoft Power BI Desktop.
Docs: 
Combine files (binaries) in Power BI Desktop 
Folder