Normally when you rebuild your model, the feature checks any adjacent edges or faces that it is touching.
Sometimes a normal rebuild will not display errors higher up in the feature manager tree. This is when you would go into Tools / Options / System Options / Performance and turn on the option for "Verification on Rebuild' and then on your keyboard hit CTRL-Q.
This will force SolidWorks to rebuild your entire feature tree from top down. It may reveal errors that were not present before.
You may need to use this technique when doing advanced surfacing or other advanced modeling techniques. If faces sometimes disappear or turn transparent for no reason, chances are you need to perform the actions listed above.