Why does the add record button only somtimes appear?

[Matt_Lister]

Does anybody know why the plus shaped “Add New Record” button, only sometimes shows on a table?
On some tables it is there:

And on some pretty identical tables it is not:

I thought it might be to do with sorting, grouping, table permission, width of table. But they all seem to vary leaving me feeling like it’s totally random. Does anyone know the anwser to this mystery?

Thanks
Matt