Emulator

That's EXACTLY What I Did, and it STILL doesn't work.
Copied the RMCE01 folder from Dump to Load directly, everything intact. Still doesn't work.

shrug I don't know why it isn't working for you. I got it to work.

What is the full file system path that your textures are stored in?

C:\Users\jimbo1qaz\Documents\Dolphin Emulator\Load\Textures\RMCE01

Or am I not supposed to use the "Textures" folder? The Graphics/Advanced screen says to keep the Textures folder.

Oh, and I have texture cache set to the middle option. Does that influence the problem?

In addition, there is a bug with DX11 where _mip1/etc. files are dumped as the full resolution file, instead of the proper mipmap. When I redump and reload the textures under DX11, I still cannot load custom textures.

http://jimbo1qaz.ro.lt/files/RMCE01.7z. I modified the full-size rainbow texture, but it doesn't show up ingame. That worked in 3.5, though, using a TGA file, as I have already said.

Use PNG

@parlane: That's not an answer. If we in any way regressed in regards to custom texture support, it would be nice if we at least knew that instead of saying "oh my, yeah that might have happened, well whatever so we don't support that stuff anymore".

However, given that the issue report is very vague on steps to reproduce this from a clean Dolphin installation with a clean user directory, I don't feel like wasting any time on it.

Dolphin 4.0-479 retest:
Clean slate.
-Enable OpenGL.
-Disabled Emulated Wiimote 1.
-Set up GC Controller.
-Do a VS race of Luigi Circuit
-Check Dump Textures just after pressing OK.
-Copy all dumped textures to the LOAD folder
-Draw a large horizontal line across RMCE01_eee0550a_14.png in GIMP
--It does not show up.

Dolphin 3.5 trial:
(DX9)
-Disable Emulated Wiimote 1.
-Set up GC Controller.
-Copy modified texture from Dolphin-Dev, convert to TGA
-Do a VS race of Luigi Circuit.
--Modified texture does NOT show up.
Redumping textures under DX9:
-Do a VS race of Luigi Circuit, stop emulation at begin of countdown.
-(Nope, same file)
-Replace skybox(keep it a PNG this time)
-Still doesn't work.
Redumping textures under OGL old:
-Doesn't work.

Weird, now 3.5 doesn't work either.

Maybe a build from the custom_textures_fix branch helps: http://dl.dolphin-emu.org/builds/

If that doesn't help, given that MaJoR had no problems I'm assuming you're indeed just doing something wrong.

http://jimbo1qaz.ro.lt/files/Dolphin%20Emulator.zip