I had this:

/home/karlo/.dropbox-dist/libz.so.1: version `ZLIB_1.2.3.3' not found (required by /usr/lib64/libxml2.so.2)
Failed to load module: /usr/lib64/gio/modules/libgvfsdbus.so

And the icon did not show the sync-arrows.

Disabling proxies worked for me. Right-click the db icon, settings, … you’ll find it.