You are using a custom citation style in the document. Does the problem still occur if you switch to something like Vancouver? If it does not it means there is a problem with your citation style.
If you delete the old links and insert the same new ones instead, the problem disappears. Old links in a text document have lost connection with links in Zotero. Why did this happen?
If you saved the document as .odt then the links will be lost. You have sent a copy of the .odt document to us too. Make sure you save it as (.doc), you might need to go back to a previous version of the document if you want the links returned. Otherwise see the debugging broken documents steps.
(https://www.zotero.org/support/word_processor_plugin_troubleshooting#debugging_broken_documents).