Groups not being populated by children correctly in SVG export

[mandrewpowers]

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Describe the bug
Found an old issue (#3960) about groups not being preserved in SVG export and noticed it should be happening since v24.6.0, but it seems there is an issue now where groups are being added to the exported document although they are not populated properly.

To Reproduce
Steps to reproduce the behavior:

1. Go to draw.io
2. Open a blank diagram
3. Group a bunch of random shapes
4. Export as SVG (all options disabled)

Expected behavior
All grouped shapes are encapsulated by a <g> element representing the grouping.

Screenshots
Exported SVG:

No plugins:

You can see the group element was exported, but none of the child objects are within the group.

If I export using the svgdata plugin and add custom cell identifiers I see the same result. This also does show that the plugin does not seem to add the metadata to the original content but instead wraps it more.

Recreated with svgdata:

I noticed this issue when working on a large floorplan and exported the SVG to display elsewhere with interaction. Since the groups didn't actually wrap the elements none of the interactions worked so I dug into this a bit.

Multiple groups not wrapping any content:

draw.io version (In the Help->About menu of the draw.io editor):

• draw.io version: Web v26.0.3

Desktop (please complete the following information):

• OS: Windows 10
• Browser: Firefox
• Browser Version: 133.0.3

Smartphone (please complete the following information):

• Device: N/A
• OS: N/A
• Browser: N/A
• Browser Version: N/A

I tested the problem in incognito/private mode with all browser extensions switched off, write "yes" below:

• yes

Additional context
Add any other context about the problem here.