One day, after forming links throughout ~30 pages document, I found some of them broken. They look like this
https://s3.amazonaws.com/zotero.org/images/forums/u11983190/9jmx2b18sangayzxvo63.png

Zotero plugin doesn't work at all.
What happened? Is it known issue? Is it possible to avoid in future?
This stupid bug makes the using of Zotero literally a nightmare.