If you’re using the BBCSO templates, note that you should change the “Length %” on the Legato switches to some number greater than 100%, to make sure the scripting triggers legato because of overlapping notes. Out of the box it’s left at the default of 100%, and with humanization jitter you get some odd jumpy results. This should be done with all the instruments which have legato - woodwinds, brass and strings.
Note there’s also an override in Playback Options Overrides which specifies a default legato length to use.