The following is only seen in SketchUp for Windows 2026 - all fine when opened in 2025.
Existing large model that has been similar size and fine for more than two years. Same applies if I delete almost everything and purge unused on a copy of the file. Same applies to affected single objects cut and pasted into a clean new model file, though new groups can be created correctly in the clean file.
To recreate: With nothing selected and nothing hidden, right click blank area and Make Group; Draw a rectangle; Extrude to a 3D box; Click away to close the group. NB: If you create geometry first, then group, this issue does not arise.
What is seen: The new box suffers a lot of visual clipping or spontaneous disappearing when zooming; It cannot be selected by clicking on it, because the bounding box is displaced. Using selection rectangles in a wide area ‘finds’ the bounding box so the bounding box and geometry appear blue; Cannot ungroup, as right clicking on the object misses the bounding box and deselects and clicking on the displaced bounding box does not find anything.
If I open the file with these displaced groups in 2025 it all looks normal with correct bounding box.
ADDED: Although this issue only arises for me in 2026, I think the source is some feature of this particular model file. I have not been able to recreate it in several other older SKP files that had not previously been opened or worked on in 2026.
The steps you gave don’t show an issue, you may have missed a step. For example, if you have used push pull to extrude the rectangle, you say to click away to close the group, but that doesn’t work. Did you switch to the select tool at that point? Did you do any save actions during the steps?
There was a known issue on iPad and web, where if you did a save while inside a group, that the saved model would have recorded the bounding box incorrectly. That only happened on iPad and web for a short period, before we fixed the problem. But, that meant some number of models already had the problem, and so SketchUp 2025 had a fix in it to take care of such models.
As the problem wasn’t around for long, the fix was removed from SketchUp 2026, in the hope that affected models had been worked on since the earlier fixes.
But, there could still be work flows that might lead to the same problem. One we’re looking at is the importing of DMG files, we haven’t found an example that shows the problem yet.
Anyway, are you able to do a screen recording that shows all of the steps to make the problem happen?
For now, you can fix such groups by exploding them and making a new group.
I get the problem if I make objects in your file, but not if I copy your geometry into a new file. I will try more tests.
To explode a group that is selected, that becomes unselected when you right click, can be done from the last menu item in the Edit menu. That is a duplicate of the right click menu for what is selected, and you can choose Explode from there.
I can confirm your last workaround of Explode via main menu then Undo works for me too and is a good practical fix for now, along with using the old method of creating some geometry then grouping it.
Weirdly, I’ve just re-opened my main large model where all this began, and found the rogue groups are currently fixed, without using the workaround or any other deliberate tinkering. What I had done last night was carry out some move and rotate operations on them in SKP 2025, but didn’t check or notice this at the time.
Just successfully replicated something like that on the sample file you have, by picking one of the rogue objects and rotating it in 2025, then re-opening the file in 2026. Not only was the object I rotated fixed, but others I hadn’t touched were also fixed ‘by themselves’. You can see all this in a new screen capture here: Unique Download Link | WeTransfer
Since doing the above I have found the fix comes simply by saving the file in 2025 then reopening in 2026. In a further test I followed the process as the video above, but in 2025 just drew a new rectangle in empty space and deleted it via Undo, then saved the file.
