13 June 2020: It is looking more likely that MixCoins.com is a scam. They no longer allow withdrawals without providing ID verification and emails to their support address yield no reply.
Mixcoins is an online bitcoin exchange that offers access to the Mixcoins Bitcoin (BTC) Arbitrage Fund. It is run by an entrepreneur named Mike Gropp.
24 November 2020 Update: One reviewer on the google play store has also indicated they are unable to make withdrawals:
I’ve written this article chronicling my experience with BitBays and Mixcoins: https://howigrowmywealth.com/the-mixcoins-com-bitbays-com-scam/