Macbook Pro Does Not Sleep When Lid Closed

Hi,

This depends on the current state of your Mac whether it goes to sleep directly or stays active. In some cases your Mac stays active to cool your system down, sometimes even on battery, or to finish an ongoing backup or to sync some things. This may be part of "Power Nap" (https://support.apple.com/en-us/HT204032) and is intended to keep your Mac up to date even if you don't use it at the moment or is system related in case of cooling and extends your device lifespan significantly. If your Mac stays awake after disabling "Power Nap" you may detach external monitors. If enabled your Mac can also wake up from network, check your energy settings in this case.