Power Query not detecting last column in xlsx files

Hi 

For the past fortnight, Power Query has failed to detect the last column in the Excel source files (xlsx) which underpin our Power BI dashboards.

I have not been able to solve this in Power BI e.g. by rebuilding the queries, reloading the source files etc.

The source Excel files typically have a blank first column, which has not historically posed an issue as all columns have been detected. If I delete this blank column in the original file - or even delete it and then reinsert a blank column - Power Query recognises the last column again.

Is this is known issue and is there a solution that does not involve modifying the source files?

Thanks in advance