Safari - can't create new bookmarks

I've been trying to find a solution to this problem for the last few days, but without success.

I have plenty of bookmarks in Safari, but for the past while (I can't say exactly when this started - maybe a month ago?) I can't add new bookmarks. If I go to add, I can edit the info, click add, but nothing is actually added.

I've looked through other similar threads and tried steps listed there (i.e. unlocking file permissions and resetting them as outlined here Cannot delete or add bookmarks in Safari 8.0.3 on my iMac ) and I've also verified the permissions on ~/Library/Safari/Bookmarks.plist and it shows I have access to read and write.

Any help would be appreciated!

My specs:

OS X 10.10.3

Safari 8.0.5

iMac 5k