Requirements for level 3 offices?

[the--dud]

I often struggle in my cities to go from level 2 to 3 offices and I'm not really sure what the exact requirements are, does anyone know?

Before anyone asks, no I didn't get the notification about needing more educated workers

For instance I had a grid of level 2 offices, max land value, nearby cargo and passenger terminals and everything else I could think about... Basically it was a perfect location as far as I could see but all the buildings had some progress to level but said "requires more services". I also have fire, police, health and education close by.
If I added more bus and metro stops lines nearby the progress bar to level 3 would increase but never quite hit level 3... I even tried putting an airport nearby in desperation!

This video I made is actually unrelated but it has a really good example of this if you pay attention to the office zones near the middle.

 

[AmpsterMan]

Do offices export products? If so, perhaps building a cargo terminal nearby will help them

 

[akaBruce]

I've had the problem and I think I found the answer. This method will certainly increase that blue bar, but sometimes it's also just a bit off.

Try raising the budget of the Police, Firefighter and Medical to 150%. This helped me a lot.

Another thing that I have found to reduce the bar is noise pollution.