Is there a way to restore a field (in views) which has been removed using 'this block (override)' I am working with a view that has several sub-views and several fields which are common to all sub-views.  I removes a common field from one of the sub views by selecting it, setting the designation drop-down to 'this block (override)', and clicking the remove button.  This removed the field from the sub view without effecting any of the other sub-views (or the main view.)  I realized the I made a mistake when I removed that field and I would like to restore it.  Is there a way to revert an override on a view field that is no longer available on a sub view?  I would like to avoid re-adding a common filed to a sub-view (which will only be used for that sub view.)
You can basically revert the fields on the sub-view back to the master settings and list by:

-- clicking on the down arrow on the top right of the FIELDS section.

-- In the popup, change the For dropdown value to Revert to Default. This should effectively bring back the master list of fields, assuming that's where your missing field is.

-- any customisation for this specific view's fields must be re-done.

This same process can be done on any of the panes on the view's edit page - /admin/structure/views/view/my-view - if you want to revert anything.