I have created a test user in Amazon WorkMail, and I created a group that contains this user. I created an alias for the user as well. I created also two additional email folders for the user. I setup a rule in the WorkMail web client that moves the email to one of the folders when the message is sent to the group email address. This works as expected. I setup a second rule which moves the email to the second folder when the message is sent to the user's alias email address. However this second rule does not work. The message set to alias always ends up in the Inbox.
I used a test domain provided by Amazon.