Hi All

I'm having a problem I've not seen in excel before (Office 365) when dragging formulas

An example of the problem is something like this. I have a spreadsheet with say 2 sheets

In sheet1 column A I have data, every 5th line is a name of something
In sheet2 column A I have a formulas such as

=Sheet1!A1
=Sheet1!A5
=Sheet1!A9
=Sheet1!A13

My issue is that when I drag this down the column it's not incrementing as expected (or has in the past) it does do the increments in 5, it's just the first new dragged into jumps back a few numbers....i.e it looks like


=Sheet1!A1
=Sheet1!A5
=Sheet1!A9
=Sheet1!A13
=Sheet1!A6
=Sheet1!A11
=Sheet1!A15
=Sheet1!A19

Any help would be appreciated as it's driving me crazy