Issues with changing scheduling dates in plan

[Michael Wray]

This recent answer seems to resolve my question regarding changing the scheduling dates to custom date fields; however, once I select my custom fields they are not found in the dropdown options of the "scheduling" view (though there are many other options from Jira projects across my organization). I feel I must be missing some step here but can't figure out what I've done wrong. I posted some screenshots in a reply to that older answer.

https://community.atlassian.com/t5/Jira-questions/Timeline-view-and-Start-and-Due-Date/qaq-p/2470958#U2808058