modem-at broken because of mixed use of GSimpleAsyncResult and GTask

When I do mmcli -m 0 --3gpp-register-home with Huawei E1732, I always get timeout error. The following is printed at the daemon side:

(ModemManager:6525): GLib-GObject-WARNING **: 09:01:13.869: invalid cast from 'GTask' to 'GSimpleAsyncResult'

(ModemManager:6525): GLib-GIO-CRITICAL **: 09:01:13.869: g_simple_async_result_propagate_error: assertion 'G_IS_SIMPLE_ASYNC_RESULT (simple)' failed

(ModemManager:6525): GLib-GObject-WARNING **: 09:01:13.869: invalid cast from 'GTask' to 'GSimpleAsyncResult'

(ModemManager:6525): GLib-GIO-CRITICAL **: 09:01:13.869: g_simple_async_result_get_op_res_gpointer: assertion 'G_IS_SIMPLE_ASYNC_RESULT (simple)' failed

(ModemManager:6525): GLib-GIO-CRITICAL **: 09:01:13.869: g_dbus_method_invocation_take_error: assertion 'error != NULL' failed

I have some issues getting a good bt. Here is what I got anyway:

3  in g_type_check_instance_cast of /lib/x86_64-linux-gnu/libgobject-2.0.so.0
4  in mm_base_modem_at_command_full_finish of mm-base-modem-at.c:468
5  in modem_3gpp_register_in_network_finish of mm-broadband-modem.c:4549
6  in handle_register_ready of mm-iface-modem-3gpp.c:500

Thanks