Pushover notification fails because 'field "message" cannot be empty'

[mlazzarotto]

I've just configured Pushover to send notification on Zabbix 6.4.5, but it's not working because it says Pushover notification failed: field "message" cannot be empty.
I have 1 trigger action to send me both a email and a pushover message.
I don't believe that the 'message' field is empty because the email works well.

To configure Pushover on Zabbix I used the default parameters when creating the "Media type", except for the API token.

The "message template" has the default fields

[mlazzarotto]

Nevermind, the firewall was blocking connections to api.pushover.net.