Scheduled Refresh not refreshing one table

So I have a report with several fact tables, the biggest one which I will call Sales has about 15 million rows. Scheduled refresh runs daily (import) and isn't updating this one table. I will try my best to explain what has happened.

On my report I have a measure that returns the monthly sales value, the value for August 2023 is about 2.6 million. Yesterday I got complaints from the business as it was only showing as 1.8 million. The scheduled refresh had completed successfully. I hit the refresh button on the report to refresh the visuals, nothing changed. I refreshed the dataset, nothing changed. I then refreshed the visuals again and this time the value updated to 2.6 million. 

The next day after the refresh completes the number drops back to 1.8 million. I hit the refresh button on the report to refresh the visuals, nothing changed. I refreshed the dataset, nothing changed. I then refreshed the visuals again and this time the value updated to 2.6 million. 

2 days in a row the same thing has happened. I can't keep manually refreshing the datset and refreshing the visuals. Does anyone have an idea what the issue could be?