Finding updates for multiple references doesn't work properly

I have over 1000 custom references, which I imported from my own file.

So the format of many of the references does not match that of Endnote.

Then I select many references and click “Find Reference Updates…”.

After the software find the first update, I click “Update All fields”, then answer ‘yes’ to let the program do the same for the rest.

But, it seems that many of the references are not updated.

Because if I select the same set of reference and do the same thing again, then it will find many reference to update again.