Try to move these elements (first find by ID) to Main Model. And then synchronize.

Or if not helped - try to copy elements to another new project (first find by ID), delete from the actual model these elements. Then synchronize. If ok then copy back to actual model and try to synchronize one more time.
Oleksii Sokolovskyi | Олексій Соколовський
BIM Manager & Consultor | BIM Менеджер & Консультант
Autodesk Developer Network Member
Revit in Ukraine Co-Founder
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