Automator apps as Login Items not working
I confirmed that the same thing occurs on my system. One Automator applet runs perfectly, two or more seem to result in nothing happening.

The workaround I found was to make an Automator application called "Login Items", and have this Automator application run the others (by using the "Run Workflow" action to call each one). Testing this it seemed to work perfectly.

Alternately you could combine the actions of each Automator application into a single long Automator application, but I prefer the granularity the first option provides.