Ardour freezes after opening an LV2 plugin's GUI the second time

Under Arch Linux, with suil 0.10.16-2 installed from the official repositories, Ardour v6.9's UI becomes unresponsive when I open an LV2 plugin's window (e.g. Vitalium or Surge XT), close it, and open it again.

When this happens, the following messages appear in Ardour's terminal output:

(ardour-6.9.0:2187): GLib-GObject-WARNING **: 14:41:47.937: cannot register existing type 'SuilX11Wrapper'

(ardour-6.9.0:2187): GLib-CRITICAL **: 14:41:47.937: g_once_init_leave: assertion 'result != 0' failed

With suil 0.10.12-2, I don't have this problem.