I play on PS4 and I have verified that I have collected all the walnuts and it still says 129/130. Does anyone know how I can fix it or if it's going to be fixed soon?
You can not fix it, not having file access, sorry. The bug affects all platforms, but only those with file access can repair the damage done by the bug by editing the save file.
As to when it will be fixed, we do not know that either.