Successful submitting orders response but bet not placed

[wmash]

On 30/01/2021, I had an anomaly in that I received 3 successful responses from the Exchange API when submitting 3 different orders that indicated the orders were matched but when checking on the exchange, no orders were ever placed. All orders were placed on the same event (30256142) but different markets (1.178557935, 1.178557934, 1.178557890). They all received a similar successful response & had a similar request. Below is the req/res for 1 of these:

Request:

{
    "marketId": 1.178557934,
    "instructions": [
        {
            "selectionId": 1222346,
            "orderType": "LIMIT",
            "side": "BACK",
            "limitOrder": {
                "size": 18.24,
                "price": 1.34,
                "persistenceType": "PERSIST"
            }
        }
    ]
}

The response to the above request was:

{
    "status": "SUCCESS",
    "instruction": {
        "selectionId": 1222346,
        "limitOrder": {
            "size": 18.24,
            "price": 1.34,
            "persistenceType": "PERSIST"
        },
        "orderType": "LIMIT",
        "side": "BACK"
    },
    "betId": "223062149319",
    "placedDate": "2021-01-30T14:08:37.000Z",
    "averagePriceMatched": 1.34,
    "sizeMatched": 18.24,
    "orderStatus": "EXECUTION_COMPLETE"
}

I have always judged that if the 'status' is "SUCCESS" then the status of the order is in 3 possible states:

1. Matched (of which 'orderStatus' would be "EXECUTION_COMPLETE")
2. Unmatched/Partially matched (of which 'orderStatus' would be "EXECUTABLE")
3. Cancelled (of which 'orderStatus' would be "EXPIRED")

I thought that this was a one-off anomaly but the same issue has occurred twice today (07/02/2021). To me, this looks like the orders should have been placed & fully matched. What am I not seeing & has anything changed?

---

EDIT:

This issue happened again today (18/02/2021) whereby I had a successful response to an offer with "EXECUTION_COMPLETE". I looked in the UI when this happened & I saw the lay bet in 'My Bets' section & that it had been matched but the status was 'Void'. How is it possible that the status is 'Void' & yet it says that it has been matched?

Offer:

{
    "marketId": 1.176888211,
    "instructions": [
        {
            "selectionId": 127991,
            "orderType": "LIMIT",
            "side": "LAY",
            "limitOrder": {
                "size": 20.31,
                "price": 1.46,
                "persistenceType": "PERSIST"
            }
        }
    ]
}

Response:

{
    "status": "SUCCESS",
    "instruction": {
        "selectionId": 127991,
        "limitOrder": {
            "size": 20.31,
            "price": 1.46,
            "persistenceType": "PERSIST"
        },
        "orderType": "LIMIT",
        "side": "LAY"
    },
    "betId": "224728764659",
    "placedDate": "2021-02-18T18:06:49.000Z",
    "averagePriceMatched": 1.45,
    "sizeMatched": 20.31,
    "orderStatus": "EXECUTION_COMPLETE"
}

After the event ended, when I checked my 'Account Summary' page on the exchange, the bet had vanished. This is a major issue for my application &, I'm afraid, that my application cannot be production ready with this issue. I have looked again at the API docs for JSON-RPC API & I can't see anything that has changed so what is the issue here?