Update from Support - it's a known issue and will be fixed in an upcoming release. Details are ...
Our Escalation Team have just replied to us and we are glad to tell you that we've come up with a solution.
This is a known bug issue. It will be fix in the patch E at the end of October.
As a workaround, we would advise that you uninstall KSOS 7 and reinstall KSOS 6.
To uninstall KSOS 7, follow the guide here: https://support.kaspersky.com/common/uninstall/12783#block2
Then, download the installation file for KSOS 6 here: https://box.kaspersky.com/f/0d4ab130dc534dbd9792/?dl=1
Otherwise, you can opt to unregister office_antivirus.dll by following the steps below:
1) Disable Self-defense of KSOS 7: https://support.kaspersky.com/14816#block2
2) Open cmd as Administrator.
3) Copy and paste the following command: regsvr32 /u "C:\Program Files (x86)\Kaspersky Lab\Kaspersky Small Office Security 20.0\office_antivirus.dll"