Do you have the exclusions in place for SWS directory with SEP system ?
Similarly, Do we have the SEP processes configured in SWS No-Access list as well ? {Until SP8 MP2 we use to configure the No_Access in appstreamcfg.txt . But starting 7.5 the No_Access processes needs to be configured in registry under} - HKLM\System\CurrentControlSet\Services\AppStream\Parameters.
Also Could you please post us with the exact build number of SEP used ?. We code-fixed a comparable instance but with a different symptom in SP8 family in the past (SEP failing to insall in the presence of SWS and reversing the order helped to workaround).