A couple of weeks ago Canon released firmware v1.3.2 for the Canon EOS 5D Mark IV. It was a minor firmware update, but earlier this week Canon pulled the firmware. The exact reason Canon pulled it was unknown at the time.
A Canon Rumors reader has sent me communication from Canon USA that explains why the firmware was pulled.
From Canon USA
Firmware version 1.3.2 caused a phenomenon when using the self-timer shooting (10 seconds) with the electronic sound set to “ON” where the timer will repeat for 10 to 3 seconds and does not shoot.
This firmware version has been removed from our website and a current fix is being implemented. This fix is expected to be released in the first half of June, there is not an exact release date available at this time.