I thought that the 'refresh' button was supposed to generate a new seed as well? It sounds as though similar problems have been reported, so I'll wait to see if .19 fixes the issues.
My map generator preview screen seems to have multiple issues. (see full screen capture) Issue 1: The preview screen obscures the resource sliders. (see detail) Issue 2: The preview screen obscures the Play button Issue 3: The terrain generated does not change. Clicking the 'refresh' button will ...