Finally got it compiled, but all it opens is a grey screen

I finally I got it compiled, but all it opens is a grey screen which says: "Monster Mash: New Sketch-based Modeling and animation tool", and it hangs in there. Any ideas what could it be?

Start by reproducing the reported behavior from the compiled application and confirm that it opens to the grey screen with the shown title. Investigate the startup path and available runtime output to identify why the application hangs, then verify that it reaches its normal interface instead.

Written by the indexing model from the issue text.