EMB-500 First Officer reported landing gear aural warning and Crew Alerting System message on approach. Crew abandoned approach and referenced the QRH and landed safely after manual landing gear extension.

Narrative

Flying the visual approach for RWXX into ZZZ; we were flying the profile and had completed the before landing checklist. Weather was VMC. Flaps were set position 3 for landing; and gear was confirmed down and locked 3 green. On final approach for RWXX we received a landing gear disagree Crew Alerting System (CAS) message and 'landing gear' aural warning. Indication was now that nose gear down and locked; right main gear down and locked; and left main gear had a yellow square. We called for and completed a go-around; and contacted ZZZ Approach. During the go around the landing gear was cycled up. ZZZ approach asked us reason for the missed; and we told them we had a CAS message. They vectored us around for the ILS XX at ZZZ. After the go around; we ran the QRH - which told us to cycle the landing gear handle. On vectors back around for the ILS XX; we put flaps 1 then landing gear handle down again. Once the handle was down; we had indication of nose gear down and locked; right main down and locked; and left main was a red X. The QRH called for a manual extension. We completed the manual extension and slipped the aircraft to fully complete manual extension; but the left main was still indication not down and locked. A second go-around was opted for and we contacted approach; and told them the nature of our issue. Since the gear was not down and locked; the QRH directed us to prepare for a partial gear up landing. We briefed the QRH while being vectored around for RWXX; and as we were on a right downwind the left main all of a sudden indicated down and locked. We notified approach that our issue was resolved and we had landing gear down; 3 green. We requested the visual; since we had the field in sight. A traffic pattern was flown for RWXX landing gear remained down and locked; and landing was completed safely without incident.