I have an issue with a very simple substitution of a greek beta with an alternate beta when it is in the beginning of a word (so I have the following substitution: sub space beta' by beta.alt; inside the liga feature) but I noticed that the substitution works only when the word before the space is also greek (e.g. δοκιμή βιϐλίο ― correct beta substitution) and doesn't work when the preceding word is not greek (e.g. test ϐιϐλίο ― no substitution at all). I don't define any specific script before the substitution (e.g. script DFLT; or script grek;). Any ideas why this is happening? Thanks in advance.