tie causes a previous chord to also get tied

This isn’t a bug.
Set this Notation Option, rather than fighting it with Force Duration.

Alternatively, apply Force Duration to the previous chord before tying the G.

Hi vanmeule,

Since Dorico SE does not include the ability to change the notation options, you have to work more with force duration in order to get the note grouping you want. In your example you need to force the duration of the chord before the G2 you are tying. By tying the note in question you are changing the metric value of the notes in the bar and Dorico will use it’s algotithm for grouping the notes, unless you use force duration.
Regards
Rafael

Hi vanmeule
How are you entering the notes? I see that the string propertie is active. As a test, i have deleted the unison and then reenter it with the interval popover (see gif 1), you see that Dorico place the notes in the correct string accordingly to the tuning you have selected, you just then need to activate the bracket propertie for the note (number) in the tablature.
Or activate and deactivate the bracket propertie as in gif 2.
Hope this helps.
Rafael