Thanks for a bug report. A semi-related bug reports are bug #752637 and bug #753764. I tried to reproduce the issue with these patches included, specifically on git master, development version 3.17.91, and I am able to change recurring events once its made a detached instance. I guess my steps were the same as yous:
a) create a new recurring event with 5 instances, day by day, in
   a CalDAV calendar
b) in the Day View: drag&drop the second instance to another time and choose
   "This instance only"
c) move to the fourth day and do the same as in b)
d) change summary of the day view for those instances from b) and c)
e) change summary for the other instance with "Apply to all instances"

Summaries are changed within the day view, I'm not editing the event in the editor.

Everything after these steps seem to be done right here. Thus I'm closing this as fixed in favour of the upcoming 3.18.0.

I have also done this scenario. After choosing "Apply to all instances" all moved events are showed again at the original time. But the previously moved events stays at the changes from step b, c and d (time, summary).

But what I mean is not the summary nor something else from the event editor. I mean the dialog under Options, Recurrences (Wiederholung in German). In this dialog all buttons and the checkbox "this event is recurring" are inactive. This is what my bug report means.

(In reply to dbet1 from comment #2)
> I have also done this scenario. After choosing "Apply to all instances" all
> moved events are showed again at the original time. But the previously moved
> events stays at the changes from step b, c and d (time, summary).

Right, that was a bug and it is fixed in the most recent version (to be 3.18.0) and I think also in the 3.16.something.

> But what I mean is not the summary nor something else from the event editor.
> I mean the dialog under Options, Recurrences (Wiederholung in German). In
> this dialog all buttons and the checkbox "this event is recurring" are
> inactive. This is what my bug report means.

Ah, I see. It's by design. Making the occurrence movable means to change the instance into a standalone object, completely separate from the series it was originally part of. In these cases the editing of the recurrence rule is allowed, because its starting completely new series. For cases where the main event has any detached instances (those are set "out of the series, but still part of it") Evolution also disabled editing of the recurrence rule. The reason is that the detached instance doesn't contain RRULE and other recurrence information which the main component contains.

This editing will be possible once the question to edit all instances or the current instance only will be asked when the editor is opened, not when the changes are to be saved.

This issue is filled as bug #544813, thus I mark this as a duplicate of it.

*** This bug has been marked as a duplicate of bug 544813 ***

(In reply to Milan Crha from comment #3)
> (In reply to dbet1 from comment #2)
> > I have also done this scenario. After choosing "Apply to all instances" all
> > moved events are showed again at the original time. But the previously moved
> > events stays at the changes from step b, c and d (time, summary).
> 
> Right, that was a bug and it is fixed in the most recent version (to be
> 3.18.0) and I think also in the 3.16.something.
> 
> > But what I mean is not the summary nor something else from the event editor.
> > I mean the dialog under Options, Recurrences (Wiederholung in German). In
> > this dialog all buttons and the checkbox "this event is recurring" are
> > inactive. This is what my bug report means.
> 
> Ah, I see. It's by design. Making the occurrence movable means to change the
> instance into a standalone object, completely separate from the series it
> was originally part of. In these cases the editing of the recurrence rule is
> allowed, because its starting completely new series. For cases where the
> main event has any detached instances (those are set "out of the series, but
> still part of it") Evolution also disabled editing of the recurrence rule.
> The reason is that the detached instance doesn't contain RRULE and other
> recurrence information which the main component contains.

Perhaps you don't understand me, but I am not sure. I don't mean the detached exception, instead I mean the events that are in sync of the normal RRULE, eg the first event. In all other programs I known there is still the possibility of changing the recurring rules such as end date, day of week etc.
> 
> This editing will be possible once the question to edit all instances or the
> current instance only will be asked when the editor is opened, not when the
> changes are to be saved.

I am sorry, but what do you mean with this?
> 
> This issue is filled as bug #544813, thus I mark this as a duplicate of it.
> 
> *** This bug has been marked as a duplicate of bug 544813 ***

(In reply to dbet1 from comment #4)
> Perhaps you don't understand me, but I am not sure. I don't mean the
> detached exception, instead I mean the events that are in sync of the normal
> RRULE, eg the first event. In all other programs I known there is still the
> possibility of changing the recurring rules such as end date, day of week
> etc.

That's okay, I understand you. I tried to describe what the code does, that's why I wrote "It's by design".

> > This editing will be possible once the question to edit all instances or the
> > current instance only will be asked when the editor is opened, not when the
> > changes are to be saved.
> 
> I am sorry, but what do you mean with this?

The current situation in the evolution is that the question whether users want to edit whole series or one instance only is done on save, not on open, like in other calendar applications. Doing the question on open will read the master event, which will be helpful. Maybe it's not necessary to fix this (bug #544813), but it'll definitely help and will make things simpler.