I agree that your configurations look acceptable but check out this Q&A:
https://answers.splunk.com/answers/455406/why-am-i-getting-dateparserverbose-warnings-althou.html
According to that, you need to remove the DATETIME_CONFIG=NONE from your indexers, which is exactly what I would try. If this fixes it, though, this really should be reported as a bug because it means that a setting that should AT MOST cause the Indexers NOT to do any timestamping, actually turns this back on.
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