WhatsApp for Huawei P20

EMUI's aggressive battery management is almost always the cause. Go to Settings > Battery > App launch, find WhatsApp, turn off 'Manage automatically' and enable all three toggles (Auto-launch, Secondary launch, Run in background). Then open Settings > Notifications > WhatsApp and confirm notifications, banners and sound are on. Finally, exclude WhatsApp from any Power Saving / Ultra Power Saving mode so it isn't frozen in the background. See how others solved this on Reddit

This is a known WhatsApp rendering glitch on Huawei devices; the audio usually still plays even when the waveform appears flat. First update WhatsApp to the latest version, then clear its cache via Settings > Apps > WhatsApp > Storage > Clear cache and restart the phone. If it persists, force-stopping WhatsApp (Settings > Apps > WhatsApp > Force stop) and reopening the chat typically restores the waveform. See how others solved this on Reddit

On a P20 without Google Play Services, an outdated WhatsApp build will eventually stop connecting once Meta drops support for old versions. Update WhatsApp by downloading the official APK from whatsapp.com/android (or via AppGallery if it's listed), then clear the cache under Settings > Apps > WhatsApp > Storage. Make a chat backup first (WhatsApp > Settings > Chats > Chat backup) so you don't lose history if you need to reinstall. See how others solved this on Reddit

WhatsApp ties to one phone number, so it registers to whichever SIM number you verify; the second SIM can still handle calls and data, but only one WhatsApp account runs per app instance. To use WhatsApp on both numbers, enable App Twin under Settings > Apps > App Twin to run a second WhatsApp for the other SIM. While abroad, WhatsApp keeps working over Wi-Fi or mobile data even if your original SIM has no signal. See how others solved this on Reddit

Since the P20 lacks Google Play Services, the Google Drive backup may not appear, so use the local backup instead: go to WhatsApp > Settings > Chats > Chat backup to create a local file, saved under Internal storage > WhatsApp > Databases. Copy that Databases folder (plus the Media folder) to a PC or new phone via USB, and WhatsApp restores it on first launch when registered to the same number. Huawei's Phone Clone app can also transfer WhatsApp data directly between two Huawei devices. See how others solved this on Reddit

This contrast bug usually comes from system dark mode clashing with WhatsApp's preview/notification theme. Set WhatsApp's own theme explicitly under WhatsApp > Settings > Chats > Theme (pick Light or Dark instead of 'System default'), and check the phone's dark mode under Settings > Display & brightness. Updating WhatsApp to the latest version usually fixes the white-on-white text for good. See how others solved this on Reddit