You installed Site Cumulative Update (CU) 43 for version 8.6.1, or CU 28 for 9.00 SP2, and the DMS Auto-summary fix is not working as expected.
You must also modify web.config of a site to activate the changes.
Add the following keys to the <appSettings> section:
<add key="ek_enableContentAutoSummary" value="" />
<add key="ek_enableDmsAutoSummary" value="false" />