[BUG][ED] Display bug in Editor when grouping pieces, pieces turn green.

[Flopsy]

I encountered this bug when grouping pieces when making other levels and the pieces would change colour to green when you use the group function. This doesn't always happen but it was pretty common.

I then returned to a contest level I made and I was going to make finishing touches, and then realised this display bug had occurred on this level, the bottom half shows how it appears in the editor preview, it didn't look like this before about a month ago when I worked on this level, I only discovered this when I loaded the level again recently.
The top half is how the level looks in the player when I load the level, so there is a clear difference between the editor and what is displayed in the player itself.

UPDATE: This seems to be more reproduceable if you group pieces then save the level. Then close down the editor and reload the level, might also be dependent on grouping more pieces together than just two. A level I was working on yesterday and reloaded today, the grouped pieces are all showing up in green.

[Guigui]

I may state the obvious but : did you check the "highlight grouped pieces" option ?

[Flopsy]

I do have the feature ticked but it doesn't explain why the pieces are out of alignment still