If I copy a group from a (source) file, I can paste it into another file, but only if the source file remains open. If I close the source file after the copy, but before the paste, Synfig exits, without pasting in the group.
I copy the group from the Layers panel with control-C (Windows). I paste the group into the Layers panel with control-V (of course, after selecting a layer, above which I want the group pasted).
I am running on a Windows 10 virtual machine (version 10.0.19041) with the latest updates, under Parallels 17.0.0 Desktop (51461, the latest version) on an iMac running OSX 11.5.2 with all the latest updates.
I don’t know if this is related to the problem I just posted, but when I successfully paste the group into a destination file, a bone in the pasted-in group does not work. The pasted group (Engineer) has a person operating a crane. The bone controls vertical position of a hook and a pulley of the crane, and a length of a lift cable that suspends the pulley. See first two images. The bone is linked to a location vertex of a group that contains the pulley and the hook. The bone is also linked to the lower-left vertex and lower-right vertex of a rectangle outline that represents the lift cable, as shown in the second image.
But, after I paste the Engineer group into a new document, moving the bone has no affect, despite the fact that the vertices of the lift cable outline, and the location of the hook group, are still linked to the bone. See third image. For completeness, I also include an image showing the bone’s parameters.
In the destination file, if I disconnect the vertices of the lift cable outline and the location of the hook group from the bone, and then re-link these vertices to the bone, everything works as expected.
Similarly, if I delete the bone in the destination file, and then create a new bone and link the locations of vertices of the lift cable outline and the hook group to the new bone, everything operates as expected.
Thus, it seems the paste does not completely paste everything into the destination file, although I can’t identify anything that is missing or wrong in the parameters pane.
Maybe synfig needs that source file in memory (RAM)… I don’t know enough about synfig internals sorry but that’s my guess.
I suspect this reported issue on GitHub addresses this already:
In one of the linked issues #1387 a user found a hack similar to yours.
“I finally found the solution.
Here is the manipulation: in a project A I created a layer linked to a skeleton. Then I copied it to a project B then I deleted the skeleton from the layer in project B. The links to the frame stay and therefore is link to non-existent bones…”
but that’s my guess.