Me and @edresson1 made some more changes and it seems to be working better now. The fork is here https://github.com/george-roussos/hifi-gan the changes are in meldataset.py
The AP values are hardcoded (so check them out if your TTS has special processing attributes) but I will change it if it ends up working okay right now I am training it and it seems to be working okay. Will update further.