Quick fixes
Update the app to the latest version from the Google Play Store
Check that Hiya Spam Blocker is set as your default phone app: go to Settings → Apps → Default apps → Phone app and select Hiya Spam Blocker
Check permissions: make sure Hiya Spam Blocker has both Phone and Contacts permissions. Go to Settings → Apps → Hiya → Permissions and confirm both are allowed.
Check battery optimization: if Android is restricting Hiya Spam Blocker in the background, blocking and caller ID may stop working. Find Hiya Spam Blocker in your device's battery or app settings and set it to Unrestricted or No restrictions (the label varies by manufacturer).
Some versions of the app may require the “Display over other apps” permission for Caller ID to appear during calls. Go to Settings → Apps → Hiya → Display over other apps and make sure it’s enabled.
Full reset (if quick fixes don't work)
Important: Uninstalling will erase your block list. You may want to take a screenshot before resetting.
Uninstall Hiya Spam Blocker
Restart your device
Reinstall Hiya Spam Blocker from the Google Play Store
If you have Premium, open the Premium tab and tap Restore
Still not working?
If you’ve completed the full reset above and Hiya Spam Blocker is still not blocking calls or showing caller ID, contact support via Settings → Help and Support in the app.