I've been noticing this since for an year that whenever there are updates for the security product (BitDefender Total Security Antivirus), the BitDefender icon in the "hidden icons" won't show up sometimes after restarting the system upon update completion. By this I am unable to manually update the application further. Re-installing the product seems to fix the issue but the same occurs after sometime whenever the product updates. The issue doesn't occur upon every updates but after some updates.