Well, I did get a different result this time, but it was a crash, which occurred as soon as the server connected with the game:
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FATAL FATAL ERROR in Room Creation Code for room rm_blank
ds_map_find_value argument 1 incorrect type (string) expecting a Number (YYGI32)
at gml_Script_live_room_loader_add_layer (line 93) - var l_rnext=instance_create_layer((l_rx+l_qinst[?"x"]),(l_ry+l_qinst[?"y"]),l_rl,l_base);
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stack frame is
gml_Script_live_room_loader_add_layer (line 93)
called from - gml_Script_live_room_loader_run_impl2 (line 15) - live_room_loader_add_layer(l_lrs[|l_lrk]);
called from - gml_Script_live_room_start (line 11) - live_room_loader_run_impl2(l_rm2);
called from - gml_Room_rm_blank_Create (line 1) - live_room_start();