Many Instagram users face this weird problem: notifications come on time but DMs (messages) are not sending. This usually happens because of connection or app issues. Your phone may have internet enough for notifications, but weak for sending messages.
Instagram notifications are handled by server push, which use very little data, but sending a DM needs a proper connection. Another reason is bugs in the app. Sometimes the app is outdated or has a glitch, so DMs get stuck. Cache problems in your phone can also cause it. Also, if Instagram temporarily restricts your account due to spammy activity, DMs might not send but you will still get alerts.
To fix it, first check internet, maybe switch from WiFi to mobile data. Then update Instagram from Play Store or App Store. You can also clear cache or reinstall the app. If your account is restricted, you may have to wait some hours or days. Basically, it’s not a very serious problem, just needs some fixes.
