If you have two notes, the first of which has an articulation, and you tie them, the articulation stays and gets put on either the first note or the last note, based on your settings.
If you have an articulation on the last note of the notes you tie together, prior to their being tied, tying the notes together deletes the articulation completely. This is regardless of setting of whether your preference is for first or last note to have the articulation.
It seems to me that consistency would be that if your settings are for the articulation to go on the last note, and there is already an articulation on the last note, it gets retained and put on the last note of the tie chain.
My hunch is that under the hood, Dorico is simply deleting all the notes after the first one and extending the duration of the first note (since without Force Duration, tying sometimes changes the note grouping itself anyway). But I would still think it should check for articulations first and then apply them. Just my thought.