This is a LaTeX maintenance problem. The recommended, though lengthy, fix is a re-install to TexLive 2018: https://goo.gl/ILCp4g
While it appears possible to update older versions of tlmgr, it appears to be tricky. https://goo.gl/E2ddvU and it ends up updating all of the *sty files anyway.
I've been running TexLive update while writing this and I see that there is indeed a newer version of multirow.sty.