Why is my Sharepoint online connection wrongly updating overtime?

Hi everyone,

I am new to Tableau and am seeking for help on some workbook I am creating.

I have an excel file on a Sharepoint that contains all my planning information (order #, expected delivery date, quantities, etc.) that I use as a data source for my tableau workbook, hosted on Tableau cloud. I have embedded my credentials and created some automated extracts to update my workbooks and dashboard every two hours, as we often change some data inside the table (and as the live connection was not updating).

I have noticed that my workbooks are normally updating over the first few days, but each and every time, at some point and for an unknown reason (and irreversibly), all my data becomes wrongly read by my workbook.

Let me explain my main issue : every time, the column delivery date starts acting weird (starts considering "null" many cells where I actually have data) and more or less 75% of the cells in this column becomes unreadable.

I have no clue why this is happening and the only solution I have found for now is when it happens, I take the local .twb file I have on my computer, reupload it on Tableau Cloud (without changing anything nor the data source) - and it starts working again for the next days.

This is a bit annoying as I can't really trust my workbook now, and I need to check every day if it keeps working or not. Has anyone already encountered this issue and if yes did they find any reliable solution?

Thank you very much for your consideration !

My best

Léonard