I did a rip with all FLAC encoders, the only problem was 'flaxe.exe'.
Please, see image below, I think is a bug (CUERipper 2.1.9):
flake.exe is an external encoder. Did you download flake (http://flake-enc.sourceforge.net/download.html).exe and make it available to CUETools/CUERipper?
see also https://hydrogenaud.io/index.php?msg=993928
I didn't know that… thanks for the clarification.
I will download and incorporate the executable into CUERipper!