The problem doesn`t occur with sitefinity 5.3.3900 version. In addition lits of improvements have been added to the site sync module.
Site Sync now effectively transfers large media blobs (up to 2 GB, because of an IIS restriction) - without consuming any additional memory.
Overall sync speed improvement (30% faster sync).
Pages, their controls and properties are sent in a single request to avoid transactional inconsistencies.
A progress bar during synchronization.
A new Synchronization.log is written during the process.
Synchronization summary information is stored into the database and shown on the last (summary) screen
the Telerik team
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