Please give me a detailed explanation on how you tested this. I just ran through a test with 5 different accounts with different sounds for each, as well as different LED. I also assed some to have an icon and some not to have an icon. Some things you need to know:
1. LED won't flash if your screen is on. This is an Android thing and nothing I can do about
2. If the LED flashes green for one account and another account had red and an email came in and you never checked the green account, it won't flash red. It can only flash one color at a time
3. If an email comes at the same time from 2 accounts, it will take the account that came first and use that sound
4. If you turned things off in the Notification Channels, they will over-ride any rules you may have.
5. If you turned off vibration or sound at the device level, that will also over-ride anything in MailDroid
I unit test this for every release, so unless I have a bad test (which is possible), I find this surprising.