My girlfriend finally got around to trying the sound profile cusomisation on her Aventho Wireless using her personal Sony Xperia XZ1 Compact (Oreo) and it was a frustrating experience. She called me in to help (a software engineer by trade) and I couldn't get it to work, either. We tried many cycles of Factory Resetting the headphones, unpairing / re-pairing the headphones via Bluetooth, force stopping and clearing the storage used by the MIY app to ensure we were starting completely from scratch. Her headphones were running firmware 1.0.44 which appears to be the latest. I even tried enabling Developer Options on her handset and testing with different A2DP profiles (AptX vs SBC, AVRCP 1.4-1.6, etc). Every time she attempted to launch the sound personalisation from the MIY app it would give an "Oops something went wrong" error message.
Eventually we gave up and attempted to use the MIY app on her business iPhone 7 which allowed her to launch the sound personalisation on the first attempt. She ran through it a couple of times and re-uploaded the profile to the headphones multiple times without issue. She absolutely loves her personalised sound profile and interestingly now that it's been uploaded to the headphone via iOS she can successfully control the application of the profile (enable, disable, select percentage of customisation) without issue on her Android handset.
Although this story has a happy ending if we hadn't had an iPhone to hand it might've ended very differently. Something to consider for prospective buyers and I hope Beyer can improve compatibility!