Polymer template not working as expected (Vaadin-grid and dom-if)

I worked with Vaadin 6 to 8 in the past. Now I’m creating a proof of concept in Vaadin 14 for the first time.

I’m creating a polymer template with the Vaadin designer. My template has a grid but I can’t select a row when clicking on it.

My template has a vaadin-grid and inside this as few vaadin-grid-column elements. When using this approach I can’t select a row.
When using @Id in my Java code and adding the list to the grid, it works correct. But this means writing a lot of code for formatting the colums etc.

How can I make a grid row be selectable while still using vaadin-grid-column?

Second problem with the same template, when using vaadin-grid-column I want to use a condition inside it:

<vaadin-grid-column width="60px" flex-grow="0">
  <dom-if if="[[isValidConfig]


But nothing is displayed. The condetion always seems to be false. Of maybe it’t not processed. What can be wrong?