MacOS 27 issues i met, please fix in the next update.

For the intermittent mouse double-click problem, go to System Settings >> Accessibility >> Pointer Control and move Double-click speed toward Slow, then test again. 

If a folder does not open, select it and press Command–Down Arrow. 

If you use a third-party mouse, compare the behaviour with the MacBook’s trackpad. Apple: Change Pointer Control settings

For Safari AutoFill, go to System Settings >> Touch ID & Password and make sure Use Touch ID for autofilling passwords is enabled. 

Then go to Safari >> Settings >> AutoFill and make sure User names and passwords is selected. In the Passwords app, verify that the website account and password are actually saved. 

If Touch ID works elsewhere but not for a particular website, try another saved login because some websites may not allow AutoFill. Apple: Autofill passwords in Safari

If Touch ID still does not work, make sure the sensor and finger are clean and dry, install any available macOS updates, and restart the Mac. 

If the problem continues, delete the affected fingerprint and add it again. 

Note that macOS can require your password instead of Touch ID after a restart or under certain security conditions. Apple: If Touch ID isn't working on Mac

This is a user-to-user forum. If you have found bugs, and want Apple to hear about them, you might want to submit a bug report here: Product Feedback - Apple .