When editing in Map Viewer, added domain values do not appear in the Create features section of the Editor pane.

Additional Information

Workaround

Workaround 1:

It is shared on Esri Community for ArcGIS Field Maps but also works on Map Viewer. The steps of the workaround are as follow:

1. Go to ArcGIS Online and click Content. Find the hosted feature layer and open its Item Properties page. Open the layer in Map Viewer Classic.
2. Click the Change Style icon for the layer and symbolize the layer using the attribute field containing the domain values you created. 
3. Ensure all domains are in the active symbology group.
4. Click the Edit button at the top of the table of contents, and click Manage at the bottom of the table of contents. 
5. Click the little drop-down button next to one of the domain values to open its Properties. Erase and add the last letter of the name. Click Save Changes at the bottom of the screen.
6. Now open the hosted feature layer in Map Viewer, click Edit, and all the domain values appear under Create features section.

Workaround 2:

To manage feature templates in Field Maps Designer, follow these steps:

1. Open the map in Field Maps Designer.
2. Navigate to the layer.
3. Tap to open the Templates tab
4. To create a new template, duplicate an existing template and make changes to the name and / or default values.

Steps to Reproduce