How to reproduce : 

1/ Create and exhaustive content (and fill owns field of repeater3levels)

2/ Create a SOLR request to retrieve the repeater3Levels of this exhaustive content. 

3/ Perform SOLR research => edit column repeater3levels

When clicking on '+' button => we can create a new repeater3Levels => OK

But it is not automatically added. 

User need to add it manually thanks to "research" button. 

=> Is it possible to add an entry by clickink only on one button ?