Since updating to OSX Mojave Version 10.14, I am experiencing an irregular startup. When I turn my MacBook Air on it starts up to the login screen. I put in my password and then the progress bar will appear; then go to a black screen. It will stay at this black screen for several seconds and then start up regularly. I've chatted with Apple a couple of times regarding this, and they said that they are aware of this problem; and that their engineers are looking into it. Is anyone else experiencing this issue?