The current version of conky, 1.10.0-1, has been a little unstable since the update from the prior version. If I remember correctly, I upgraded to the plasma 5 from kdenext before conky was upgraded, so it is difficult to say what the cause of the instability is -- I suspect plasma. On a single monitor system, usually when I press Alt-F2, the conky disappears. But it is not crashed -- Ctrl-Esc shows it is still running. So I believe it is somehow going to the background behind the plasma desktop wallpaper.
FYI here is the comparable section of my conkyrc:
conky.config = {
alignment = 'top_right',
background = false,
border_width = 0,
cpu_avg_samples = 2,
--default_color = 'white',
--default_outline_color = 'black',
---default_shade_color = 'black',
double_buffer = true,
draw_borders = false,
draw_graph_borders = yes,
draw_outline = false,
draw_shades = true,
use_xft = true,
font = 'terminus:size=9',
gap_x = 10,
gap_y = 50,
maximum_width = 345,
minimum_width = 345,
net_avg_samples = 2,
out_to_console = false,
out_to_stderr = false,
extra_newline = false,
own_window = true,
own_window_type = 'desktop',
own_window_class = 'Conky',
own_window_hints = 'undecorated,below,sticky,skip_taskbar,skip_pager',
own_window_transparent = true,
--stippled_borders = 0,
update_interval = 0.6,
uppercase = false,
use_spacer = none,
show_graph_scale = false,
show_graph_range = false,
text_buffer_size = 4096,
temperature_unit = 'fahrenheit',
double_buffer = true,
short_units = true,
own_window_argb_visual = true,
}