I think I have found a bug in Inkscape and I'd like someone else to confirm it and then I'll make a bug report.

My file is available here: https://www.dropbox.com/s/j8ad768rbi29q ... c.svg?dl=0

I created the file using an online service to convert an MS PowerPoint file into an SVG. The problem is that when you move certain objects (e.g. one of the orange ones) and then press Ctrl + Z, the object moves back but it also turns black! Any idea what is happening? If you save and re-open, the colour returns to normal unless next time you move something and press undo again.

Not sure if it's a bug really, but here's a workaround:

Set Transforms to optimized in the preferences.

Select all the objects and move them up one tap on the up arrow key and then use the arrow key to move them back down. (This re-writes all the objects in Inkscape's method. )

The object colors should remain steady.

The colors are applied via CSS classes. Inkscape doesn't fully support that yet in Inkscape 0.92.3.

Funny enough, it's even worse with the development version, although that is supposed to be more advanced in that respect. There, upon opening, the objects are all black (or rather: fill is unset) already.

What works is the following workaround:

- Open file with Firefox,
- print to file (pdf)
- open the pdf with Inkscape, do some ungrouping
- works correctly now, style is applied to the objects, not as a class.

But yes, please make a report for this. It's something that devs will be interested to know about. Undo functionality should be fixed for this.
You can also mention that the file opens with unset colors in the master development branch (or just let me know the bug link here).

(or just export to pdf from powerpoint, that should be quicker for the next one)

Thanks for the workarounds. I made a bug report for the issue: https://bugs.launchpad.net/inkscape/+bug/1763730

Thank you very much!