I've setup on a clean new machine and now it works.
The signer still need to be fixed on my side as the signed TX is not recognized but i'm able to just broadcast the raw tx.
Do you have an error log for that last part?
Guess this one:
(WARNING) Transaction.py:1263 - Unexpected nested type for TxIn 16
(ERROR) Transaction.py:1289 - Insert list has index too big
(ERROR) Transaction.py:1289 - Insert list has index too big
But could be just because the signer is on an older version and the online node is on the current testing.