rects/circles/text not exported on save as Synfig (.sif)

Steps to reproduce:

• Open Inkscape
• Open
• Save as Synfig (.sif)

What happened?

File is blank,

<canvas version="0.5" width="456.322866" height="222.027092" xres="2834.645752" yres="2834.645752" view-box="-3.802691 1.850226 3.802691 -1.850226">
      <name>non-paths.sif</name>
    </canvas>

What should have happened?

Elements are exported correctly. I'm not sure about the correctness of the file (I don't use synfig), but something does export with Inkscape 0.92.4 (8da668285a, 2020-02-28) non-paths92.sif

First reported in inbox#2040 (closed)

Inkscape Version and Operating System:

• 1.1-dev (inkscape@0b728ebf, 2020-03-15), extensions head at 1b5cc38a with Linux Mint 19.1