Can you reproduce that with all plugins disabled? If so, can you provide a Debug ID for Zotero startup through reproducing this, using the "Restart with Logging Enabled…" option?
I disabled Better BibTex (the only plugin I use) and restarted Zotero which solved the issue. Many thanks!
P.S. I re-enabled BibTex and new citation dialog still works.
And meanwhile I noticed another problem, Document Preferences dialog box in MS Word doesn't fit my screen (Macbook Pro 2015 13inch default resolution), I cannot see OK or Cancel, has to hit "Enter" to confirm selections. If I choose a higher resolution, I can see OK and Cancel buttons but higher resolution slows down my computer. (Please see below for before and after screenshots.) I believe there is too much space between lines, not just in the Document Preferences dialog box but also in the main Zotero settings, especially between headings.
Upgrade Storage
https://s3.amazonaws.com/zotero.org/images/forums/u884004/4pvqumxox7nptfresb5k.png
P.S. I re-enabled BibTex and new citation dialog still works.
And meanwhile I noticed another problem, Document Preferences dialog box in MS Word doesn't fit my screen (Macbook Pro 2015 13inch default resolution), I cannot see OK or Cancel, has to hit "Enter" to confirm selections. If I choose a higher resolution, I can see OK and Cancel buttons but higher resolution slows down my computer. (Please see below for before and after screenshots.)
I believe there is too much space between lines, not just in the Document Preferences dialog box but also in the main Zotero settings, especially between headings.
https://s3.amazonaws.com/zotero.org/images/forums/u884004/rl6jkk6pmcdyew7dty9d.png
https://s3.amazonaws.com/zotero.org/images/forums/u884004/f0vyjaer7igf3t1f8e4h.png