Objects disappear after subtraction

[Michail]

Do the following:

Open the attached file.
Select both objects.
Click on the geometry button "Subtract"

Expected: A hole
Result: Both objects disappearhe

Additional information: The object on the lower level was created by power-duplication and subsequent geometry function "Add" .

Subtract.afdesign

[Joachim_L]

The element in the background is open. Close it and it works. See image for the open nodes.

[Michail]

55 minutes ago, Joachim_L said:

The element in the background is open. Close it and it works. See image for the open nodes.

That really seems to be the reason. But it remains a mystery:

1. Sometimes the subtraction works and sometimes it doesn't, even though I always do the same thing.
2. I don't see an open knot.
3. When does the curve open? There are only closed ellipses!

[MEB]

Hi Michail,
The issue is caused by a stray point in the bottom object (in the center). Select that object, change to the Node tool and drag a square marquee around the whole object to highlight all the nodes. Delete the single one in the middle (in the center of the object). Have you created this file entirely in Designer or imported or pasted anything created in another app? Have you used the Expand Stroke command at some point?

Stray points can cause issues in Designer, unfortunately we don't have a command to clean up the file as Illustrator. I'm logging the issue/passing the file to development for inspection. Do you happen to have a previous saved version of the file with the ellipses still intact before the add operation?

[Michail]

2 hours ago, MEB said:

The issue is caused by a stray point in the bottom object (in the center). Select that object, change to the Node tool and drag a square marquee around the whole object to highlight all the nodes. Delete the single one in the middle (in the center of the object). Have you created this file entirely in Designer or imported or pasted anything created in another app? Have you used the Expand Stroke command at some point?
Stray points can cause issues in Designer, unfortunately we don't have a command to clean up the file as Illustrator. I'm logging the issue/passing the file to development for inspection. Do you happen to have a previous saved version of the file with the ellipses still intact before the add operation?

Thank you for the detailed explanation, @MEB, and for the proposed solution.

I have noticed such a middle node in other objects before. I've always wondered what a strange point this is. They all have something in common:
If I try to move this point, the program crashes.

To your questions:

1. Yes, I created this file entirely in Designer.
2. I did not import or place anything.
3. I didn't use the "Expand Stroke" command.
4. Unfortunately I do not have an earlier version of this file anymore. But I have tried to reproduce the problem in the same file. After two or three attempts the problem reappeared (see attached file). I saved the protocol in the image. For power duplicating I have to move the center of rotation. I have the suspicion that it could be related to this. What is your opinion?

Subtract_1.afdesign

[MEB]

Hi Michail,
Thanks for the file. Some operation you are performing is generating those stray points (will have to check this out). I've seen this caused by the expand stroke command on complex objects or coming from objects pasted/imported from third party apps but apparently you stumbled upon another case. Yes, moving the stray point(s) will crash the application - just select and delete the stray point without moving it. I will check your file and log this. Thanks for your support, much appreciated.

[Gear maker]

58 minutes ago, Michail said:

If I try to move this point, the program crashes.

MEB FYI I was playing with Michail's file in the beta and was able to move the center node, but when I tried to exit without saving my AD crashed.  Crash report is attached.

Crash 2-5-2020

Michail, what I did find is that when placing the position of the center, if it's slightly too far out of the proper position I did leave a center, but it didn't stop me from doing a subtract of an inner circle.  I couldn't duplicate that problem.

Have you tried to use the center position in the transform panel instead to shift the center point?

That looks like it would be what you need for your formation.  And it does it exactly where it needs to be.

Good luck.