Issue
When a document is uploaded in a document library with Nintex forms, the browse button is missing from the managed metadata field.
Resolution
The Manage Metadata control does not support browsing MMD terms when the item is opened in the pop up dialog mode.
Workaround
On document upload in a document library that has Nintex form published pop up dialog for new form is missing the browse feature for MMD control as it is not supported. Instead use the free text search functionality by typing the required term in the MMD field.
Alternatively use the "Modern SharePoint UI" as "Modern SharePoint UI" does not open the new form in a dialog.
Workaround
On document upload in a document library that has Nintex form published pop up dialog for new form is missing the browse feature for MMD control as it is not supported. Instead use the free text search functionality by typing the required term in the MMD field.
Alternatively use the "Modern SharePoint UI" as "Modern SharePoint UI" does not open the new form in a dialog.