Unknown error occured. Blivet-gui will be terminated. could not find parent for subvol

[SampsonF]

Unknown error occured. Blivet-gui will be terminated. could not find parent for subvol

Blivet-gui works initially with Fedora 27. When I keep creating btrfs subvol, and suddenly it refuse to load afterwards.

This is the "Show traceback" under Fedora 27.

File "/usr/lib/python3.6/site-packages/blivetgui/communication/server.py", line 261, in _blivet_utils_init
self.blivet_utils = BlivetUtils(*args)
File "/usr/lib/python3.6/site-packages/blivetgui/blivet_utils.py", line 189, in init
self.blivet_reset()
File "/usr/lib/python3.6/site-packages/blivetgui/blivet_utils.py", line 1335, in blivet_reset
self.storage.reset()
File "/usr/lib/python3.6/site-packages/blivet/threads.py", line 45, in run_with_lock
return m(*args, **kwargs)
File "/usr/lib/python3.6/site-packages/blivet/blivet.py", line 272, in reset
self.devicetree.populate(cleanup_only=cleanup_only)
File "/usr/lib/python3.6/site-packages/blivet/threads.py", line 45, in run_with_lock
return m(*args, **kwargs)
File "/usr/lib/python3.6/site-packages/blivet/populator/populator.py", line 454, in populate
self._populate()
File "/usr/lib/python3.6/site-packages/blivet/threads.py", line 45, in run_with_lock
return m(*args, **kwargs)
File "/usr/lib/python3.6/site-packages/blivet/populator/populator.py", line 519, in _populate
self.handle_device(dev)
File "/usr/lib/python3.6/site-packages/blivet/threads.py", line 45, in run_with_lock
return m(*args, **kwargs)
File "/usr/lib/python3.6/site-packages/blivet/populator/populator.py", line 318, in handle_device
self.handle_format(info, device)
File "/usr/lib/python3.6/site-packages/blivet/threads.py", line 45, in run_with_lock
return m(*args, **kwargs)
File "/usr/lib/python3.6/site-packages/blivet/populator/populator.py", line 345, in handle_format
helper_class(self, info, device).run()
File "/usr/lib/python3.6/site-packages/blivet/populator/helpers/btrfs.py", line 86, in run
raise DeviceTreeError("could not find parent for subvol")
blivet.errors.DeviceTreeError: could not find parent for subvol

File "/usr/bin/blivet-gui", line 115, in
main()
File "/usr/bin/blivet-gui", line 110, in main
BlivetGUI(client)
File "/usr/lib/python3.6/site-packages/blivetgui/blivetgui.py", line 101, in init
self.blivet_init()
File "/usr/lib/python3.6/site-packages/blivetgui/blivetgui.py", line 712, in blivet_init
self._reraise_exception(ret.exception, ret.traceback)
File "/usr/lib/python3.6/site-packages/blivetgui/blivetgui.py", line 219, in _reraise_exception
raise type(exception)(str(exception) + "\n" + traceback)

[SampsonF]

After I remove all old subvol, then blivet-gui is loading fine.

Fedora 27 x64
blivet-gui 2.1.7 from official Fedora 27