The Tutorial looks good, I would imagine pretty helpful to new folks. I prefer the new Turinium UI. The control group change was a good one.
After the tutorial I started a couple skirmishes and didn't have a starting engineer. Apparently the AI has no idea what to do and has built literally nothing.
I have done some testing to reproduce your problem. I opened up AotS, ran the tutorial, and first chance, exited, then started skirmish. No engineer spawned as you had reported.
Closing, and restarting AotS, the engineer spawns fine.
This could be due to the tutorial scripts starting with disabling the engineer spawn so that an engineer can be spawned in dramatically later. Exiting the Tutorial probably does not properly reset these configurations.
From my experience, the AI scripts are heavily reliant on pre-requisites, if something is missing/abnormal, then it gets stuck waiting for the requisite to be met. I am not surpised the AI isn't working if the engineers aren't spawning properly.