Hi Akanksha,
This is due to the salesforce KI here: https://success.salesforce.com/issues_view?id=a1p3A000000KOscQAG which is now fixed. Can you try and refresh from sandbox to sandbox again and let us know if the issue is resolved?
For reference: Due to the Salesforce error; any new sandbox created from an affected org that contained static resources with text fields longer than 255 characters, would result in truncating of the field, in this case the XML in all or most Skuid pages in the new org.
