Probably a duplicate of * Bug #1452560 “Rectangles missing from saved SIF” https://bugs.launchpad.net/inkscape/+bug/1452560
(see comment 6 there for the list of objects types missing in SIF files exported with Inkscape on Windows - apparently due to lack of quotes for object ids to be converted in a separately spawned Inkscape instance)
Probably a duplicate of /bugs.launchpad .net/inkscape/ +bug/1452560
* Bug #1452560 “Rectangles missing from saved SIF”
https:/
(see comment 6 there for the list of objects types missing in SIF files exported with Inkscape on Windows - apparently due to lack of quotes for object ids to be converted in a separately spawned Inkscape instance)