The add button is missing from the dependencies tab

On a host I did update from 3.2 to 6.0.0beta3 and then to 6.0.0rc2, on another host I did update from 5.4 to 6.0.0rc2

I can not add dependency between two hosts using the trigger "Unavailable by ICMP ping". The add button is missing from the dependencies tab

Dependencies created prior to the update are present