isn't [t] in longtable[t] supposed to make text align at top of rows? as in
\begin{longtable}[t]{p{0.5\textwidth} | p{0.5\textwidth}}
but I see something else happening. I can post a MWE. I did not think this worth asking at main board, since I am sure it has easy solution, but I can;t see it now.