Automatic data refresh in Power BI from web fails by changing some but not all of the data

Question

ANY help is appreciated as i am at a total loss of what to do...

I have created an automatic web-datasource that updates Power BI Service dashboard daily through the program E-conomic and their rest-api.

I am analyzing inventory data, where cost prices and inventory quantity data is extracted from E-conomic and the total inventory value is calculated in Power BI as cost price*quantity.

When I update the data in Power BI desktop, all calculations and the extracted data is correct. The same goes for the initial publish to Power BI Service. However, when the automatic update happens, either through a scheduled update or by updating through Power BI Service, most of the cost prices are multiplied by 100, so that the inventory value becomes way too high.

This only goes for about 400 out of 1800 item numbers. I tried to fix the issue by dividing the calculations by 100, but then i identified the approx. 400 item numbers, that would then result in an inventory value that is too low. I have identified the item numbers that differ by not failing in the update. Nothing ties these item numbers. I compared the item numbers that failed on two different dates, and not all of them failed both days. Some failed the first time and not the second and vice versa.

I have no idea what could be the reason for the refresh issue and any hints or possible reasons are much appreciated!

Kind regards

Anna