Hello,
I'm having the same problem when trying to use the @execute command in my custom start and end g-code to trigger custom local executables, and the above solutions don't work for me. The double backslashes disappear just like single backslashes, and the forward slash does not execute the file I specify in the code (using Windows 10). I also tried single and double quotes around the file directory, but that didn't work either.
Any other solutions for this issue? I didn't have this issue previously with older versions of Slic3r (v1.2.1 or lower), but with 1.2.2 and up this started occurring...and I would really like to be able to use the newer versions.
Thank you in advance,
Kirk