Originally reported by Comrade Mike in a post on community forum. Confirmed and filled by yvanzo.

When editing a relationship with specific credits for the source/target, on hovering the source/target's name in the preview, the tool-tip for the main name doesn't show up for area, instrument, label and place.

It shows up correctly for artist though.

(Event, recording, release, release group, and work cannot have credits in relationships.)

After further inspection, it appears that it is also broken for artist too as it was showing the sort name only (which happens to often be the same as the name for groups). Actually it is broken for all the React-rendered parts of the beta website.