I found out that an old DBX 1.x version was causing a conflict on the heavy forwarder that I was attempting to install a modular input on. Even though the DBX app was disabled it was still problematic until I removed it from the directory. After it was removed and I restarted Splunk I was able to see several many methods that were not visible before.
This other splunk answers topic lead me to this solution:
https://answers.splunk.com/answers/311245/63-upgrade-missing-http-event-collector-data-input.html
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