HI Konstantin,
I faced the same problem last month.
I solved this problem by disabled the EDIT button of the assignment block one by one.
In the OVPview ,you can see each of the assignment block and their components and views, go to .HTM OF the VIEW LAYOUT.
You will code like below,
<thtmlb:areaFrameSetter toolbarButtons = "<%= controller->GT_BUTTONS %>"
maxButtonNumber = "3" />
<chtmlb:config displayMode = "<%= controller->view_group_context->is_view_in_display_mode( controller ). %>"
mode = "RUNTIME" />
<div style="display:none" id="EmpResName">
<thtmlb:inputField value = "//Campaign/RESPONSIBLE_NAME"
visible = "FALSE" />
</div>
If you want to hidden the button,you can clear the GT_BUTTONS.
If you want to display only , you can set the displayMode to abap_ture.
Wish this can help.
Best regards.