Daniel, the results of some brief tests installing applications such as kate, konsole, konversation and krusader were not consistent with respect to adding to and removing from the dock as a favourite.
Some applications gave me both the add and remove options, one application gave just a remove option while another gave me neither option.
The work around of right clicking on a search result worked for all the applications that I tested while using Ubuntu 20.04.1.
Daniel, the results of some brief tests installing applications such as kate, konsole, konversation and krusader were not consistent with respect to adding to and removing from the dock as a favourite.
Some applications gave me both the add and remove options, one application gave just a remove option while another gave me neither option.
The work around of right clicking on a search result worked for all the applications that I tested while using Ubuntu 20.04.1.