In the integration a user has at some time saved  the view with all activities expanded. In the integration in question a lot of receive activities have been added. At some point in time the number of activities in this view has become so big, that Integration Manager is unable to expand all the activities. As a result Integration Manager terminates.

The solution is to locate the user's file called tool_integrations_15.tag.

/home/xib/local/config/tag/tool_integrations_15.tag

In this file locate the line where 690 showed up as the number attached to the anchor activity:
TOOL_ACTIVITYTREEEXPANSIONDEPTH_690=1

On this line change "2" to "1".