lyx 2.3RC1 can't find requested module

[Eran Kaplinsky]

With a new installation of 2.3rc1, LyX can't find textpos. Repeated on
another system with the same result. Reconfigure doesn't solve.

Both are Win10, fully updated texlive 2017. Lyx 2.2 loads the same file
with textpos just fine.

EK