Problem is, small front chainring is tiny on a triple, so the chain ends up really short to avoid it touching itself at the rear derailleur when on the smallest cog.
I mean, I can't see the situation when I'd ever have the chain in the small chainring and the smallest cog, but there must be a way of having the chain length so you could if you wanted but also have it on the big ring and largest cog (which I probably wouldn't use either).
Don't cross-chain.