Yesterday, everything seemed to be working fine. My last edit was of the most recent row; I added some text to a multi-line text field. I discovered this morning, the edit did not take. The text I added was not in the field. I tried again - no luck. 

I logged out of WP, and logged back in, and tried to edit the row again. When I save the row, wpDataTables indicates that it was saved successfully, but the row is not updated.

I don't see anything special about the row, the field, or the existing or added text. Other rows have similar (and more text). So I'm at a complete standstill.

I think I found the error (mine, or perhaps a documentation issue). Will elaborate in a bit.

Here's what I think is happening. I can append "hello" to the end of the field, no problem. But if I try to append "1 < 2", after saving, I do not see the less-than character or anything after that. I suspect wpDataTables is seeing "<" as an HTML meta-character, at least in some contexts.

If I enter "1 < 2" on an empty multi-line string field in that same row, it works fine. But if I enter "line 1" in that field, save it, edit again and enter " test1 < test 2" after that, I see "line 1 test 1" after saving.

I certainly haven't tested all permutations, but it seems like in multi-line string fields (and possibly singe-line string fields) with data, if you subsequently add "<" (and possibly other meta-characters), the program treats them as HTML meta-characters.

So the workaround is to use < for "<" and so forth. Strictly from a data enterer perspective, the behavior is inconsistent. In the code, everything might be fine, but figured I'd mention this, just in case this is an issue.