After zooming in or isolating objects, other objects disappear upon zooming out. I have to select and isolate invisible objects in order for them to reappear.
Sarah Khan (Illustrator team) commented
We are pleased to inform you that your request is available in the latest release of Illustrator version 22.0.
Visit your Adobe Creative Cloud Application and update. If you do not see an update on the application please check for update from the flyout options on the application after clicking on three vertical dots. For step by step process please visit: https://helpx.adobe.com/in/creative-cloud/help/download-install-app.html#Checkforupdates