I have had this problem off and on for awhile now. When i am connecting to a data file (excel or text) and i drag and drop my Data Sources on to the field in my design, instead of using the first record in the data file it is giving me a very long string of information. (see photos).
I have had certain time where this was not the case and when i mapped the data file it would display the first record as the sample data in my design.
Please note, that when i do print preview everything looks correct.