QuickDraft in 10.1.13.1 via Houdini 18.5.449 fails with variables

If I set a Houdini project with the output like this, it renders fine but fails the Quickdraft
\server\tests\houdini\render$HIPNAME.mantra1.0001.exr

It fails searching for the EXR as the variable seems to remove the trailing slash
\server\tests\houdini\render$HIPNAME.mantra1.0001.exr

Works fine with absolute path names

I have a ticket open about this