Communication service is showing me blank Keys and gives error: Something went wrong. Regenerate your keys to fix this issue.

We are facing similar issue. I am unable to finish Bicep deployment because of this.

    "status": {
        "value": "Failed",
        "localizedValue": "Failed"
    },
    "subStatus": {
        "value": "NotFound",
        "localizedValue": "Not Found (HTTP Status Code: 404)"
    },
    "submissionTimestamp": "2024-08-01T07:20:27Z",
    "subscriptionId": "...",
    "tenantId": "...",
    "properties": {
        "statusCode": "NotFound",
        "serviceRequestId": null,
        "statusMessage": "{\"error\":{\"code\":\"ListKeysFailed\",\"message\":\"Specified resource not found\"}}",
        "eventCategory": "Administrative",

For me the issue was that I have connected not completely verified domain(SPF, DKIM1/2). In portal you are not able to add not completely verified domain, but Bicep allows for that (Azure manged is always completely verified). Creation of just communication service was showing the keys. After I finished verification of all entries it started working and the endpoint and keys are shown correctly.