Nice repro!
 

Okay, so scratch the folder idea.
 
Here is a video of deselection at the end of a process (I used a simple transpose), no tracks are re-selected with an expanded range. I also redid similar with it zoomed out so I could select the entire project in the timeline from right to left, and no re-selection occurred.
 

Anderton
Now, THAT for sure is a bug.

 
Or actually, maybe not...?
 

 
 
 

mettelus
Okay, so scratch the folder idea.
 
Here is a video of deselection at the end of a process (I used a simple transpose), no tracks are re-selected with an expanded range. I also redid similar with it zoomed out so I could select the entire project in the timeline from right to left, and no re-selection occurred.

 
But you didn't do a process and extend the region per WC, you created a new one. Again, if you don't believe me, I'll do a video that shows how extending a range automatically re-selects the track/clip once it encounters one. That's what I was talking about because that's what [I thought] he was describing.
 
In the future, I should probably just refrain from trying to answer a WC post until I see the translations.
 

To add to the OP, and clarify the unfortunately ambigious term "extend the selection" -- I typically use 'select by time', and have it set to a keyboard shortcut.    So that is how I "extended the selection":   called up "select by time", and changed the end time to a different time, further out.    This is not anything special for this process, it is how I nearly always work with selected bars.  

Anderton

Anderton
Now, THAT for sure is a bug.

 
Or actually, maybe not...?
 

In your video all 3 tracks have all 3 clips.
 
In my example the second clip has no second clip and that is triggering the bug - empty spaces bugging selections.

azslow3
In my example the second clip has no second clip and that is triggering the bug - empty spaces bugging selections.

Huh?

I believe Aslow intended to say, the second Track has no clips, not the second Clip has no clips.

+1, in aslow3's example, the second track does not have the second clip in it, so when it is processed, SONAR drops track 2 from the selected group. Then when the third clip set is highlighted, track 2 is no longer processed.
 
It essentially replicates the OP better, since the tracks are "out of view," so the user is none-the-wiser that their selection has been altered.

I've seen various problems like this in other contexts, where Sonar changes the selection based on what it found inside it, instead of preserving the area I wanted to have selected. It makes predictable operations impossible in many cases.