[Defender Pro] Defender Pro Masked Login suddenly got deactivated?

Hello — I’ve been working on this website for 2 or 3 weeks right up until 12 hours ago and I always log in at my redirected (masked) URL. Now today I had to log in at /wp-admin, and see that the masked login feature has been deactivated, but not by me and nobody else has access to the site.
1. Do you know why this would happen? And how to prevent this in the future?
2. I ‘m concerned about all my other sites. Who has time to log to all of them in to see if some important security feature isn’t working?
Thanks!
Eric