Why do my investors keep failing?

So Ive been playing this game for awhile all of my investors are 4 or 5 star and all are fully upgraded and have around 70% pass rate before the update they would bring me measly investments being as low as 50 million the investments were a waste of time but they seemed to come back with a positive return almost every time now after the update they bring investments that actually make money but now they seem to fail to make a positive return almost every time and now they want 25-30 gems to recover lost funds??? I feel like the game was only giving positive returns because the amount of money before was minimal but now that I can actually earn money from them they defiantly arent investing with a 70% success rate as Ive upgraded them to have

Lazylahma about Tap Tap Trillionaire : Money!