To reproduce:
1) Open attached project and the first scene in it
2) Select each button in hierarchy one by one - notice each has an Image component
3) Select both buttons - notice you can't multi-edit their Image component
4) Open second scene in project
5) Try multi selecting different buttons - notice that some groups can be edited (for example, original 'bt', 1, 2 and 4) while others cannot even though all are same

Reproduced in 5.5.0b4, 5.5.0f3, 5.6.0a5