A family of Microsoft word processing software products for creating web, email, and print documents.
It appears to be a bug in WD2013. I've been trying all manner of option combinations, and then it struck me to just use the format painter from a table that does split, and apply the format across all rows.
It worked. Non of the visible table properties appear to have changed, so my presumption is that the issue lies somewhere deep.
Hope this helps.