Now, I start
tcpdump -i any -f "udp and port 1195"
and ping the remote end tunnel, but not a single ping is returned nor I see a single packet captured by tcpdump. The same config and device were working on some unofficial 17.07.4 build I was using previously.
Linux coffee 4.14.221 #0 SMP Mon Feb 15 15:22:37 2021 mips GNU/Linux
Are you sure that the wan interface is up? Try restarting it. You can use pbr or a vlan to bypass the tunnel for testing, if necessary. I've found that it's sometimes necessary to restart the wan interface(s) after adding a new interface.
Thanks for the suggestions, but I'm sure wan is up, I'm using it to write this response and I've verified with tcpdump that packets created with netcat with UDP and the same port number successfully leave my openwrt router and reach tunnel gateway. I tried restarting wan, but still no luck :(