This is a rather interesting one. 3.1.1 works perfect, however this bug was introduced with 3.1.2 specifically.

Sample project:
https://github.com/NathanWalker/custom-title-3-1-2-issue

Repro steps:

1. Run the app on iOS tns run ios --emulator
2. Observe the title is blank in the ActionBar at top of opening page
3. Open app/item/action-bar/action-bar.component.html
4. Take note the usage of the custom Label for the title. Now comment out both ActionItem's (see note in file) below the Label.
5. Observe the custom title Label will appear.

Bug:

Using custom Label title on a custom ActionBar component alongside ActionItem's with *ngIf will never work. This exact same setup worked perfectly in 3.1.1.