15.05.2021, 07:48 (This post was last modified: 15.05.2021, 08:14 by Selur.)
It's a bug with the CustomQTGMC addition using another value than QTGMC as 'Insert before' should work.
-> will look into it and send you a link to fixed version.
If you follow those instructions and you have write permission on the output folder a debug output should be created, if not some program on your system is interfering. (virus scanner or similar may be?)