Hi @picktwomedia,
I hope you are doing well today!
There are a few steps you can take to address the issue with Defender malware scan not working;
Check for plugin conflicts- Deactivate other plugins and see if Defender starts working. If so, reactivate the plugins one by one to find the one causing the conflict.
Check for theme conflicts: Temporarily switch to a default WordPress theme (like Twenty Twenty) and test if Defender works. If it does, there might be an issue with your current theme.
Please make sure you have recent backups and perform this operation on your dev/staging site if possible.
To learn more about a plugin/theme conflict test, please see this guide below:
https://wpmudev.com/docs/getting-started/getting-support/#conflict-test
Try to increase WordPress memory and time limits, in some cases, the issue might be caused by a lack of server resources.
Please make sure to add below code just before the line
/* That’s all, stop editing! Happy blogging. */
set_time_limit(600);
define('WP_MEMORY_LIMIT', '512M');
define('WP_MAX_MEMORY_LIMIT', '1024M');
Also you can try uninstalling and reinstalling the Defender plugin to ensure you’re using the latest version and that there aren’t any file integrity issues.
Kind regards,
Zafer
