I was able to get it nice after changing the PAL to NTCS.
That's a useful data point.
Dont really know what else it might do. Is it possible to have it working with PAL?
It should be possible to fix, but the code looks like it's set up to handle both the same way, so we'll need some additional information.
I've attached a test script which will collect some information.
You must set "Enable Lua Native Calls" in the CHDK miscellaneous menu before running the script.
Please run the script, with the camera in shooting mode (not playback/image review) once with HDMI connected and format set to NTSC, and once again with it set to PAL.
It will create a file called m3vtest.log in the root of the SD card. Please post that here.
Note this script is only for M3 with firmware 121a (or sx730 100d which I used for testing, since I don't have an M3)
AFAIK NTSC vs PAL shouldn't affect HDMI out per se, but according to the manual, it changes the available frame rates in various video recording modes. I don't know if it also affects live view frame rate.
I tried to take a dumb from camera and have a file called "M0132.CTG
I'm not clear what this refers to, the M****.CTG files found in DCIM/MISC are something the canon firmware does related keeping track of image files.