peewee order_by failed
The update from 2.x to 3.x has a lot more changes than just that:

http://docs.peewee-orm.com/en/latest/peewee/changes.html
I installed a new version of Ubuntu and with that also peewee version3.7.1
Now the order_by meta declaration in the models does not work anymore.
I had to add order_by statements in the queries.