We recently ran into some issues where we could not export a Sharepoint 2010 list OR successfully edit it in datasheet view. Even though the list is fairly big we have not issues with other lists of the same size.
When exporting to Excel we get the error:
An unexpected error has occurred. Changes to your data cannot be save.
When editing in datasheet view we get the error:
Cannot connect to the server at this time. You can continue working with this list, but some data may not be available.
Some content online suggests the issues relate to AAM, date or people fields. We tried the various suggestions with no luck. In the end our solution was to remove the grouping on the view. The list in question had a grouping on 2 fields and after removing it we could export and edit in datasheet view.