When an app has no themed icon

Not every app on your phone will have a Zenith icon, and that is expected — the pack themes the apps it has mappings for and leaves the rest untouched.

• What you see: an unmapped app keeps its normal, unthemed icon, sitting alongside the themed ones. Nothing breaks; the app is simply not part of the pack's table yet.
• Why it happens: either the pack has no icon drawn for that app, or it has the icon but not the exact component name your phone's version of the app uses. Component names differ across app versions and phone makers, which is why one app can be themed on one phone and not another.
• What you can do now: assign any pack icon to that app by hand (see assigning a single icon) so it matches the rest of your screen. There is no in-app "request an icon" screen in the pack — the app has no interface for it — so treat hand-assignment as the immediate fix.

See also. Troubleshooting