I've encountered that the sorting of Ecom groups in frontend is no longer reflective of the manual sorting in backend. Instead, groups are displayed alphabetically in the group list of the product catalog app. I've asked support about this and been told that this is the default behaviour from 9.9 and onwards.
Is there any workaround? The API for the group class doesn't seem to provide a property that holds the manual sort order.
We have a customer for whom this is pretty criticial, so we've made a quickfix adding a custom sort order field to the groups that we can sort by. But it's pretty tedious to maintain.