Scan Failed

I am running the latest version of WP and Wordfence… for the past week I have been getting this error:

The current scan looks like it has failed. Its last status update was 14 mins ago. You may continue to wait in case it resumes or cancel and restart the scan. Some sites may need adjustments to run scans reliably. Click here for steps you can try.

I have tried all of the steps suggested in the link… this is happening on all of my sub-domains and i am unable to resolve this… can you please help, we have been hacked 2 times since this has been happening so it is causing a lot of problems.