Endnote not registering in-text reference

Some of the references I have previously inserted into my text are not being registered by Endnote when I attempt to alter them (eg add another author/text to the reference). Although the affected in-text references are visible and highllights when I click on them, when I attempt to alter them nothing happens.The texts are still in my library but it does not appear to register their existence in my text. If I want to alter the in text reference, I have to re-insert the reference. This does not affect al of my references and seems to happen randomly. Any suggestions would be handy. I am using x3 on a Mac. 

What do you mean to alter them?  To add another citation?  or to alter the citation text and reference itself?  If you are trying to add an additional citation, don’t try putting in the existing citation, but adjacent to it (with no space). 

Are you saying the you cannot select “edit citation”? 

If your endnote fields are actually corrupted, I would contact Tech support immediately. 

Sorry, when i write alter I mean to simply add another citation. When I select ‘Edit Citation’, the ‘Edit Citation’ box comes up but instead of it automatically highlighting the specific citation I am trying to add to, it highlights with the first citation in the document. When I scroll the citation list down to find the citation I am attempting to add to, it is not in the list (although it is in my manuscript and indeed highlights when you click on it in the manuscript). Any suggestions? Many thanks.

You shouldn’t have to “edit citation” to add a new citation.  You want to place your cursor next to the original formated citation (not in it) and go to your library and select the new citation you want to add, and “insert citation” from either the endnote toolbar or the word tools.  - just like you did to put in the original.  If there is no space between the two, they shoudl get combined immediately if CWYW is enabled.  Note, that in X4, if you jump to the library, once you have references cited in the manuscript, it only shows those refs currently used in the document until you switch to “all references”. 

I think we’ve got a little off-track from my original problem that there are citations that are not being registered as existing. Hence, when I insert a citation by clicking the cursor next to the existing citation, Endnote merely adds a new bracketed citation, rather than adding it to the citations already there. By comparison, using a different method, when the existing citation/s are highlighted and I attempt to insert another citation, the original citation/s are deleted and replaced by the new one, leading me to reinsert the original citation/s. This problem appears to occur to random citations and I unsure why. If this is a glitch then I can live with it, but if there is something I have done wrong or that can be fixed I would like to know. Either way, your advice is appreciated.