Error "Data refresh took too long to complete"

[Enigma]

Since the past week I am facing issues with date refresh on my report. I had a scheduled refresh set for twice a day and since the last week it has failed many times. Today, the scheduled refresh was disabled after it failed for four consecutive times. The below error is shown

The refresh operation failed because it took too long to complete. Consider reducing the size of your dataset or breaking it up into smaller datasets.

The same happens when I refresh manually from the Service as well.
These failures have started since the last week. The refreshes have been running since almost a year. There have been no changes to the queryies, tables structure, schema or code. 

The size of my dataset is merely 3MB. Data sources are couple of Excel files and one SharePoint list. The files have ~17k rows in total and the list has ~30k rows. To me it doesn't look like a large dataset and I am not sure is the time out caused by the size or complexity.
I have a Pro license.

From the Desktop when I click Refresh, the excel data gets loaded instantly, but the SharePoint data takes close to 30 minutes to load

[GilbertQ]

Hi @Enigma 

You can use Power Query Diagnostics to look further into this

Power BI Query Performance & Query Diagnostics – Paul Turley's SQL Server BI Blog

[GilbertQ]

Hi @Enigma 

What I would suggest doing is to see if you can reduce the steps when getting the data from SharePoint?

Or if you can seperate the data etc to run quicker and easier.

[Enigma]

The steps are already reduced to the optimum. Not sure if I can further bring it down. 
Do you think the size of the dataset is an issue though?

Also, I was trying to setup an incremental refresh but am getting the below warning

The link given asks to run Power Query Diagnostics, but I am not sure how to read the diagnostic report.

[GilbertQ]

Hi @Enigma 

Even though you get that warning it can sometimes still do the incremental refreshing. So I would give it a try and see if it works?

[Enigma]

Yes, I went ahead with the Incremental Refresh despite the warning.

But it did not work. The refresh failed with the same message "The refresh operation failed because it took too long to complete. Consider reducing the size of your dataset or breaking it up into smaller datasets."

I am sure the root cause lies with the pulling of the SharePoint list data. But can't pin point it at the moment. Are there any plug-ins/tools that will indicate which step is taking more time?