When you say you “imported” the output style file, what exactly did you do? The Endnote support page instructions for installing individual styles is listed as the following:
1.Download the style you want to install.
2.Double-click the style file. It should open in EndNote.
3.In EndNote, go to “File Menu” and choose “Save As”. Replace the word “copy” with your style’s name and click “Save”.
4.Click on “File Menu” and choose “Close Style”.
Also suggest you save backup copies of your thesis more so when dealing with external cloud drives. Save a copy where the Endnote citations have been unformatted so they appear with the curly braces (a.k.a. temporary citations).