When publishing to or adding an item in ArcGIS Online, the field names are truncated to the first 32 characters.

Workaround

• In ArcGIS Online, navigate to the Data tab of item details page and click Fields. Click Add, specify a name with 64 characters, and click Add New Field. The new field name retains all 64 characters.
• Use the Calculate tool to copy the old field values to the new field. 

Steps to Reproduce