Harmy said:

I downloaded a program called Briz LUT Converter and used it to convert the .cube to .3dl and that loaded fine in AE - but the Briz converter trial only lets you convert 10 files and then you have to buy it - I don't know if there's any freeware that could do the same thing.

Here are the .mat, .cube and .3dl files from my test, so that you can check them out DrDre:
http://uloz.to/x5Qg2nnT/luts-rar

Thanks! I think the problem is due to the delimiter, and/or number of decimals. The tool has been updated, and the LUT now matches the LUT produced by Briz converter, so it should work. I'm waiting for wetransfer to send the link.