I've been having numerous occasions where Zotero connector in Firefox (which has always worked spectacularly smoothly) will not save a reference to my library by any of the optional methods. Moreover, several subfolders in the "My Library" directory show "Error loading list" although my group libraries are available. My storage is almost full, but I'm trying to manage with what I have. Unsure how any of these issues might be related. My recent usage pattern to save space is I back up as usual locally but usually delete the archived pdfs. I have just also tuned off automatic sync. All problems remain.