SubTotal for Sum function returning zeros

[ForestFeeder]

I have a data table ( originally pulled from another spreadsheet using SQL
query - probably irrelevant to the issue ).
When I try to SubTotal with the sum function it incorrectly returns zero for
all results. The cell formats are number. Any idea what's going on here ?

 

[Teethless mama]

Post your formula and your expectation

 

[ForestFeeder]

It seems that the data IS IN FACT text, even though the properties of the
cells are number! I confirmed this by copying a row to another worksheet. The
data pasted as text. It did inform me as a warning in the pasted row that the
data was stored as text.
So, how can I truly set the data to NUMBER ?
P.S. the formula is =SUBTOTAL(9,E6:E8)