Have a friend attempt to connect via the F8 panel. They can do this by typing “connect [server IP]”. If they can’t join, it means you made a mistake with port forwarding - otherwise, you may of unlisted it in server.cfg
sometimes if you type hearthbeat multiple times in the console ( Not in-game console, but the vps/zap what ever you are using),it should show up eventually. Had a similar issue a while ago, even though it said it is sending hearthbeats. Also, make sure your language settings, tags and etc are valid, as sometimes that can cause it not to show up