Troubleshooting BGP routes not being installed

[nett_hier]

I have set up a Kubernetes cluster with MetalLB using BGP to share routes, with the cluster residing in 10.3.1.0/24 and MetalLB announcing IPs in 10.3.1.100-10.3.1.199.
I have configured the OPNsense host as a peer in the cluster, and the cluster nodes as peers in OPNsense.
For the peers in OPNsense, I also created a prefix list permitting the network 10.3.1.0/24
The BGP peering seems to be successful and messages are being exchanged.
However, no routes coming from the cluster are being applied.
I have recorded the packets coming into the interface on the OPNsense host and noticed multiple UPDATE BGP packets containing routes such as this one:

Meanwhile OPNsense reports 0 prefixes received and the logs do not seem to contain any useful information either.
How can I further troubleshoot what is going wrong here?

[nett_hier]

Seems like the prefix list was the problem. Setting it to none in the neighbor settings fixed my issue.
How do I make a proper prefix list though? The one I used contained 10.3.1.0/24 as the network and then apparently refused 10.3.1.100. Am I misunderstanding how these lists work?