OpenVPN traffic blocked by default?

[Narva]

I've tried to setup OpenVPN in my Opnsense from "factory defaults" by following 3 different guides, but every time I end up to the same situation:
Not a single UDP package is coming back from Opnsense to the OpenVPN client.

These are the networks I have:
Home router LAN: 192.168.1.0/24
Opnsense LAN: 192.168.20.0/24
OpenVPN tunnel: 10.0.0.0/28

The wiring is as follows:
Opnsense WAN (192.168.1.2) <-> Home router LAN (192.168.1.1)
OpenVPN client (192.168.1.3) <-> Home router LAN (192.168.1.1)

I've disabled private and bogon networks filtering from Opnsense WAN interface.
I've enabled logging of all firewall rules.
I've checked the "allow access to OpenVPN" rule exists in WAN firewall rules.
I've check the "allow all within OpenVPN tunnel" rule exists in OpenVPN firewall rules.
I've checked the "allow access to OpenVPN" rule is used by monitoring firewall live logs.
But not a single deny rule is logged while OpenVPN client is trying to connect the OpenVPN server.
I've monitored OpenVPN client traffic and observed that not a single UDP package is coming back from the Opnsense.

The only solution so far has been disabling the firewall totally (Firewall -> Settings -> Disable all packet filtering).
After that the OpenVPN client establishes the connection instantly.
And there are no firewall rules in the home router to restrict traffic between LAN clients.

I'd say there's some kind of default system rule which is blocking the traffic and I'm not able to find it.
What am I missing here? What could be the problem?

The 3 different guides I've tried:
Instances: https://docs.opnsense.org/manual/how-tos/sslvpn_instance_roadwarrior.html
Legacy: https://docs.opnsense.org/manual/how-tos/sslvpn_client.html
Legacy Wizard: https://sysadmin102.com/2023/08/opnsense-openvpn-remote-access-ssl-tls-user-auth/

Opnsense version: 24.7.5_3