You need to clarify that you added Window20=MINI PANEL (as advised in my email) and that it's not included by Captain Sim.
Besides that, with, or without, this window, you have still have the same problem - I cannot get the MINI PANEL to work/display on any version.  It shows as "WINDOW 20" in the Panel Config.  At best it display for less than an instant.

It appears that this is blocked by the Main Panel (Window00=Main Panel). If I go to the Cockpit View (default F10), press SHIFT+1 to remove the Main Panel, then press "W", the Main Panel reappears. So it's possible that something in here:

[Window00]
size_mm=1024,768
background_color=0,0,0
position=4
visible=1
render_3d_window=0
ident=MAIN_PANEL
gauge00=Captain_Sim.c130.sound!main, 0,0,10,10, Captain_Sim\130\sound.ini
gauge01=Captain_Sim.c130.main!main, 15,0,10,10
gauge02=Captain_Sim.c130.electric!main, 30,0,10,10
gauge03=Captain_Sim.c130.fuel!main, 40,0,10,10
gauge04=Captain_Sim.c130.left!main, 0,0,1024,768
gauge05=Captain_Sim.c130.engine.analogue!1, 753,391,271,377
gauge06=Captain_Sim.c130.radar!RADAR, 617,217,157,158
gauge07=Captain_Sim.c130.engine!fdump, 0,0,1,1
gauge08=Captain_Sim.c130.ramp!smoke, 1,1,1,1
gauge09=Captain_Sim.c130.engine!mod, 1,1,1,1

is the cause. Worst case, it's in the gauge code, so only the removal of the gauge from the panel, will allow the Mini Panel to appear and remain on the screen.

Thinking this through, I wonder if any of this:

[VIEWS]
VIEW_FORWARD_WINDOWS=MAIN_PANEL,RADIO_STACK_PANEL,THROTTLE_PANEL,GPS_PANEL,10115,11000,11001,11002,11003,11005,11006,11007,11008,11009,11010,11011,11012,11013
VIEW_FORWARD_DIR=8.0,0.0,0.0

could be a cause? It would need to be tested to see if it was. :-/