Excel not recognising header row

[KPTame]

Hi, I'm using Office 365, and have a fairly old spreadsheet originally compiled in an older version.

I'm trying to sort the data; I tick the box that says my data has header rows, and this is ignored.  The header row is being sorted.

There are no cells frozen, the header row is bold, and I've made sure the spreadsheet is saved into the latest version of Excel.

What can I try next?

Thanks all.

[#2]

@KPTame 

Could you attach a sample workbook (without sensitive data), or if that is not possible, make it available through OneDrive, Google Drive, Dropbox or similar? Thanks in advance.

[#3]

Thanks for your speedy reply.
As a workaround, I pasted the header row into another sheet and deleted it, and sorted the data with no header row. All was well.
Then I inserted a row at the top, and pasted my headers back again.
The spreadsheet is now sorting perfectly. Very strange. Taking the header row out and putting it back seems to have cured it.
KPT

[#4]

@KPTame 

Glad you found a workaround/solution.