Custom date field values are saved but not displayed on the detail page

[jwalgran]

Reproduced on production
iOS app version 2.7.0
Web app version 2.18.1

• Create an instance
• Add a custom date field
• Log into the iOS app as the instance creator
• Add a tree and set a value in the custom date field
• Save, click away from the tree to unload it, click to load it and check the detail page

Expected: The custom date value is displayed
Actual: The custom date field is empty on the iOS app, but the detail page in the web app shows the correct value.