Few Sales orders Object link is disappeared in cProjects

Hi All,

I am getting issue in eProject .When I open a project in eProject object link is disappeared for few sales orders I am not able to see the object link.

To see missing object links in project now I am creating manually then I able to see the  object link.

Any one have idea why few project not showing object link sales order.

Please see the screen shot.

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Object links is missed below screen shot.

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Clik here to view.

I checked in below link 'own persistence' not checked.

Created Object link is disappeared

Thanks,

Preddy.