AGOL does not honor my coded domains when uploading a hosted feature layer

[AndrewCiurro]

I have been trying to upload several layers which include domains on certain fields so that I  can use drop down menus on my Crowdsource Reporter app. However, upon uploading and getting them to work with my Crowdsource Reporter app, the drop down does not appear. I went into the definition of my hosted layer and saw that the field domains have been assigned as "null". Here are some photos pointing out my problem.

Snapshots of the Field Properties page to prove they've been assigned the domains:

And of the Domain Properties to prove they've been assigned to domains that exist:

[AndrewCiurro · Accepted solution]

The solution was to share the map as a service to my organization through ArcMap rather than zipping the file geodatabase and uploading it back onto AGOL. I was using zip files based on this documentation​. However, if you follow these instructions​ for hosting a feature layer from an arcmap document, it will keep the domains intact. This documentation for ArcGIS Collector (which I'm not using for this project) also outlines the same instructions.

Even though it's assumed people using Crowdsource Reporter have experience working with AGOL, it might be useful to update the instructions (found here) with items like "How to create a dropdown list" instead of only saying "Use coded value domains to have drop-down menus" with no more mention of drop-down menus after that. Sharing an arcmap document versus uploading a zipped file gdb are somewhat nuanced differences that aren't very intuitive to users new to hosting data on AGOL.

The solution to this question was found on StackExchange: link​.