So, I updated Last night, and saw the issue today morning ( I didn't reboot after update ). As already mentioned, bug is in Cinnamon itself, and has been fixed.
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Temporary Fix
Right click on desktop and click on open in terminal. Now enter command
cinnamon-settings
This should open Settings and then, go to panel > Panel visibility , and set it to always show panel.
Click back on terminal and press ctrl+c to close settings. Now enter reboot command to reboot.
It should be fixed after the reboot.
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Permanent Fix
This bug has already been fixed by Cinnamon devs. Refer
Thanks for opening issue at right place. The issue will resolved as soon as package is rebuilt and available in repository.
Thanks !
!