Is there a way to see the responses sent by contacts to surveys and check if there is no data missing?
February 2014 and newer releases
You can find the responses sent by contacts to your surveys by accessing the standard report 'Survey Responses By Contact' (ID 7018). The same report can be accessed from a specific survey by opening the survey and accessing the Results tab.
If you have more than 10,000 rows when running the Survey Responses By Contact report, the results will be displayed in more than one page. When trying to visualize the last responses received by sorting the report based on Date Created column, you will only sort the results of that specific page. This might cause the impression that there is data missing. However, that data that can be found on the next pages.
The limit of 10,000 rows is controlled by the configuration setting VRL_HARD.
Specifies the limit of the number of rows that can be displayed in a report. If the number of rows returned exceeds this number, the remaining results will not be displayed. Default is 10000
Path to setting(s): Select Configuration from the navigation area > Site Configuration > Configuration Settings > and search by Key.
More information about how to limit the number of rows displayed in a report is available in the answers:
Answer ID 5422: Report results limited to 10000
Answer ID 1763: Viewing more than the first 100 records in a report
Sorting the Date Created column of the report Survey Responses By Contact will only have an effect per page and it will not sort the entire report in case it's processing more than 10000 rows or if you set VRL_HARD to a smaller value.