I just tried it, and it worked for me with a very large paragraph.
I think you're pushing the edges of what Data Merge can do, and on a larger project would probably hit the limit.
Check out David Blatner's Lynda.com video on Data Merge and Database Publishing (10 day free trial):
I've had cells truncate in conversion from .xls to .txt or .csv. but never seen a problem in ID merging whatever is left in the cell.
For what it's worth, my data source was a .txt doc that I created in TextEdit. It was a paragraph in column 1, and a single word each in columns 2 & 3, and I only made one record.
Great, thank you all for your replies, it is much appreciated!
I was working on a project that contained 200 diplomas and there were 4 fields to fill out by blending data. The big problem that occurred in Indesign was related to the amount of data contained in two fields that had more than 250 characters. This information simply was not directed to their respective text boxes, as was predicted, simply, all information was concentrated in only one field.
Uncovered problem: If your text contains commas or semicolons, the information will not be entered properly in each field (appropriate text box, it will simply be directed to just one text box).
Resolution of the problem: If your text contains commas or semicolons, you must insert double quotes ("field information") at the beginning and end of this content. Ready!
Hope this can help someone ...
Note: Sorry for the poorly written text, but I do not speak English.