Everdo 1.2.2 on Ubuntu 64bits.
In ‘Next’ for instance, when I group items by projects, leave Next to look at something else (Inbox, whatever) and go back to Next, my ‘group by’ preference is forgotten and items are grouped by default.
I reproduced this behavior with items in Someday too. I guess it is the same for Waiting and Scheduled but I don’t have any Project items there.
It gets reset when you switch to a list where grouping by project is not supported, for example “Inbox”, “Scheduled”, “Projects”.
Maybe it’s possible to avoid this, I’ll have to check.
I believe each list should have an independent grouping option.
Manual choosing grouping option depending on the list that is currently viewed is actually against productivity 
The biggest issue I see when I switch from focus to a particular tag (e.g. contact).
Focus list is more clear when we use grouping by project but when we want to look at everything which is assigned with the particular person it’s better to use default grouping which allows us to see different sections: next actions, waiting …
You make good points. I think this Improvement has already been added to the list for development.
There is another thing.
Why when I “star” a whole project or notebook it appears on focus list as standalone action? There should be a separated section for projects and notebooks.