PREVIEW_RENDERING_FAILED - intermittent error

Have seen this posted a couple of times with no resolution.  Working on a large scale site, where the Embed API has been working well for months has in the last week started popping up with the error PREVIEW_RENDERING_FAILED, which fails to even show an error message, instead we get a completly blank screen.

The files are loaded from an API and converted to a bytearray returned via a promise, which  has not changed in any way, and the files sometimes load and then sometimes we recieve a blank screen and the error above. The files are not larged, max is currently around 2MB and the only way i can consistently show the error is if i 3G throttle the connection, just seems to time out even with small files.

The error seems to be thrown in ViewSDKInterfaceApp.js on line 54, which shows:

    previewFile(fileInfo, previewConfig) {
        this._logExternal("Starting process to preview file.", fileInfo.metaData, previewConfig);
        return this._embedModeHandlerService
            .initialiseAction(fileInfo, previewConfig, IFrameMessageTypes.PREVIEW, hostAppStartTime)
            .then(() => this._adobeViewer.getExposedAPIs({ previewConfig }));
    }

There are also some XHR requests going to https://dc-api.adobe.io/system/log which seem to have some additional information:

{
  "level": "error",
  "message": "Error in preview, file rendering timeout",
  "sessionId": "41188030-6b8f-47f9-9ab2-3b6dca66d104",
  "viewSDKAppVersion": "REDACTED",
  "tenantId": "REDACTED",
  "callingApp": "dc-view-sdk",
  "externalUserId": "REDACTED",,
  "clientId": "REDACTED",
  "client_timestamp": "2023-08-22T19:45:58.200Z",
  "context": "AppStore"
}

And

{
  "level": "error",
  "message": "File preview blocked as preview failed to load REDACTED",
  "sessionId": "REDACTED",
  "viewSDKAppVersion": "3.2.4_3.2.0-bab76ff9",
  "tenantId": "REDACTED",
  "callingApp": "dc-view-sdk",
  "externalUserId": "REDACTED",
  "clientId": "REDACTED",
  "client_timestamp": "2023-08-22T19:45:58.253Z",
  "context": "App"
}