[Describe the issue you're reporting.] The sync doesn’t work on IPad.
I added several papers into my Library on MacBook and I found that it can successfully synchronize to the web library but not to iPad. Also, I built up new collections on my Mac zotero. It works great on web library (everything goes to there), but not on my iPad zotero. It only shows the collection with nothing inside.

I use Jianguoyun.com with WebDAV for sync storage, and exactly same account on all devices. The iPad zotero shows verified server, and three months ago it smoothed worked. So, I don’t know how to fix current issue.