If it was after March 12th, 2019 then you knew it will be on Epic and as you stated you purchased the game on Epic.
From our FAQ: I purchased Phoenix Point from the Epic Game Store, can I trade/get a discount for a Steam key?
We do not offer a trade-in program or discount for Epic Game Store or other game store purchases.
One advice I can give you if you have problems with Epic is to play Phoenix Point without Epic Games Launcher. It is DRM free. You can play it even without internet. Just run the game from the .exe file on your PC. In my case, it is D: Program Files\Epic Games\Phoenix Point\ PhoenixPointwin64.exe