Changing scopeAttributes in a .tm_properties file i.e. adding
[ *.tex ] scopeAttributes = 'attr.save-on-deactivate'
does not update scope attributes in open files. Only .tex files opened after the .tm_properties change will carry the new scope attribute. Not sure if this is a bug or not, but it is worth noting as it does confuse matters when trying test attribute-specific commands :-).
Cheers,
David.