Ion-select disappears

i have a little wizard, guiding user through 3 “pages” with some inputs.
Technically I have a service and a component.
The component have 3 sections shown with *ngIf=“step == 1” (step==2, step==3).
If a user clicks the “next” button my step counter increases and the next section is showing up.
The backbutten decreases the step variable.

My Problem:
In section 2 I have an ion-list with ion-inputs and one ion-select with multiple flag. If I select some values it shows “value1, value2” in the list .
When I go to section 3 and then go back to section 2 the ion-select shows only " , ". If I click on that input field and the alert dialog shows up the list shows “value1, value2” again.
(I’ve got the same issue with an ion-select with multiple flag set to false).