Troubleshooting Transform Failures

I’m in the process of migrating a very complex transform from ElasticSearch to OpenSearch, and it isn’t going as smoothly as I would have expected (min and max aggregations on date fields in OpenSearch produce ridiculous results like -Infinity and 1.620755626993E12).

The _explain endpoint does not provide any helpful information when debugging issues with transforms:

"status" : "failed",
      "failure_reason" : "Failed to index the documents",

Where are useful errors being logged? I have re-run the transform twice, and both times it stopped very close to the same spot, so I’m sure its an edge case my cleanup pipeline isn’t handling yet, but having a faster way to get pointed to the errors would make a world of difference.