Mantle Sepolia node unable to submit transactions

[frangrech]

Hi, we are running a Mantle Sepolia node. It is able to fully sync successfully, however whenever we try to execute transactions using the node, they remain pending. I can see the transactions in the node's txpool, where they remain pending and never get queued. For other op-stack nodes, usually there is OP_GETH_SEQUENCER_HTTP environment variable or --rollup.sequencerhttp= flag set for op-geth, which links to the sequencer, and that the node uses to submit transactions. This is not set for Mantle Sepolia, and I suspect this is the reason why transactions remain pending.