vlookup of a value returns "#N/A" when value is found and format seems correct

Hello, I have a vlookup formula that is returning "#N/A" to the cell although the value I am looking for has been found, but for some reason it doesn't pick it up.
However, the value "1004" in this case to be found in the matrix, is lined up to the left of the cell, and if I open the cell, click in the formula bar after the value "1004", and then press return, the value realigns to the right of the cell and then the formula result is correct. If I open and click each cell it realigns and it works, but I have thousands of cells in the column so I must find the root cause.
I though it had to do something with the formatting but I have applied the same format to the lookup value as to the value on the matrix list, and it still does not work.
Any ideas?
Thank you.