You macro code looks fine.
Which version of UltraEdit/UEStudio do you use?
Since UE v12.20 and UES v6.10 the GotoBookMark and GotoBookMarkSelect commands have been modified, but with some bugs if not at least UE v12.20a+2 is used.
Also maybe better would be to use PreviousBookmarkSelect instead of GotoBookMarkSelect which I just have seen.
Are you sure that every date string is found only at start of a line and never anywhere in the middle or end of a line. If you are not sure, use the command UnixReOff at start of the command to select the UltraEdit style regex engine and modify Find "^c" to Find RegExp "%^c". Don't forget to add UnixReOn or PerlReOn at the end of the macro to switch back to your preferred regular expression engine, if it is not the UltraEdit engine.
Which version of UltraEdit/UEStudio do you use?
Since UE v12.20 and UES v6.10 the GotoBookMark and GotoBookMarkSelect commands have been modified, but with some bugs if not at least UE v12.20a+2 is used.
Also maybe better would be to use PreviousBookmarkSelect instead of GotoBookMarkSelect which I just have seen.
Are you sure that every date string is found only at start of a line and never anywhere in the middle or end of a line. If you are not sure, use the command UnixReOff at start of the command to select the UltraEdit style regex engine and modify Find "^c" to Find RegExp "%^c". Don't forget to add UnixReOn or PerlReOn at the end of the macro to switch back to your preferred regular expression engine, if it is not the UltraEdit engine.
Best regards from an UC/UE/UES for Windows user from Austria