Uncaught (in promise) Error: Invalid request

Trying to execute a contract method like a simple transfer fails with the following error. No dialog pops up for approval.
Similar behavior in iPhone AlphaWallet.
I guess this could be related to a custom network I added to test my app because when I deploy the same contracts to Ropsten AlphaWallet works fine.
When I run the same app from desktop browser MetaMask works fine.