After taking a break from ACEO for a few months, I’m now building a new large airport and wanted to share some thoughts - and report some issues, I’m dealing with.
First of all: THANKS FOR THIS AMAZING SOUNDTRACK!!! It’s great, perfect tracks, various styles, I really love it - and I hope it will be extended, in the future! 
Being able to assigne vehicles to stands/depots is a great thing! And I really like the extensions of restaurant areas! Looks amazing and works fine, love it! Several other small improvements, I appreciate the progress this game made, once again!!
Nevertheless, there are some bugs or misbehaviours I’ve noticed:
-PAX are standing around, far away from anything. Fully equipped airport, but a dozen, or two, PAX are standing around at an (unsecure) area far away from anything and doing nothing. Of course, they are late at boarding, finally…
This one is really annoying, as I’ve bug-reported and mentioned already in Dec '18, here Airport CEO Alpha 29 released - #143 by sirhc80 , and it is still not solved…
-At my gates which are most far away from security checkpoint, there are always PAX late. When tracking them, I find them on the other side of my airport (in secure area), far, far away from their gate. As any facilities needed are available nearby their gates, there is no reason, why they are running around at the other end of my airport. nearly every flight at these gates is affected, at about 3 to 15 PAX per flight are extremely late.
-When single (late) PAX arriving at boarding desk, they stop for a while, about 2-5 seconds, a few tiles in front of boarding desk, before they start boarding. looks weird and worsens delays.
-After playing a while, like more than an hour or so, PAX and staff are starting strange behaviours. staff doesn’t reach it’s job in time, large amounts of PAX don’t arrive at my airport and/or don’t check-in, don’t go to security. My process monitor looks similar to this: Airport CEO Alpha 30 released - #189 by StarshipUK
Save and reload solves the problem.
If I ignore it and go on playing, after a while ALL PAX and ALL staff stops moving and freezes.
Save and reload solves the problem.
-GA isn’t refuled properly. I have one fuel truck per GA stand and enough fuel, but every week, or so, one GA-plane complains about not being refueld.
-and, finally, a very, very old problem: planes are still not sent away but waiting for late PAX, even if setting is made to send away.
I read a lot about progress and what I’ve missed, but it’s very likely, that I missed some topics, so please forgive me, if I’m mentioning issues, which are already discussed.
But I would be happy, if the community or devs could give me an update, if these issues are already known and/or worked on.