We did a Portal Migration from On-Premise SharePoint to Office 365 SharePoint online. and all went well except few issues raised by end users as they supposed use this portal for many workflows and other automations.
First issue is that some of the fields are invisible in Edit/New Forms when editing or creating records in most of the lists. All these were well functioning in On-premise SharePoint 2010.
These fields were seen in any views (Custom/All Items) too but not in Edit/View Forms.
Enabling “Content Types” from List Settings –> Advanced Settings and then Looking at the Content Types under the List Settings, there were only one Content Type which is Default “Document” Content type and clicking on it showed only two fields added to it. So this is the Point !
Document Content Type is the default Content Type here and the custom fields were not added to it. This is the cause of the issue.
Simply Adding the necessary Fields in to this Content Type would save our day.
And Yes, the Forms then appeared to contain all the fields it supposed to have.
Microsoft Cloud Infrastructure Technical Journal 