I’ve two minims tied across a barline. When I select that tied note and click to add a staccato mark, the mark places itself on the last note, when I want to appear on the first.
I can’t find a way to place it properly and I don’t know why Dorico is doing this.
Please could someone tell me what I’m doing wrong? I’m reluctant to ‘correct’ this in Engrave mode, as the accent would still be associated with the wrong rhythmic position.
There’s an Engraving Option controlling this behaviour on the Articulations page, under the Ties category.
Because it is proper, for staccato. It shortens the duration, so what sense would it make on a tied note?
You can also modify this on an individual basis instead of globally if needed too:
Just curious - the notation is a bit nonstandard (staccato tied half notes). If your aim is to end the note at a specific beat point in the second measure, just make sure there is a tied eighth note at that location, like this:
To my knowledge, Beethoven puts staccato marks on woodwind minims in Eroica.
A staccato at the beginning of a held note implies that a momentary impulse (ostensibly louder than the rest of the sustained note) should be sounded. - Like singing “Taa” rather than “Aaa”.
(Duration shown in my example is correct.)
Thanks so much FredGUnn, that’s the ticket! 
Why does the subject header say “Accents” when the question is about staccato?
Of course, and I’ve even seen staccato semibreves in Wagner. But not on a note that’s tied! If you do see that, I should know about it. Staccato is not a type of accent. Your description is of an accent (of which we already have at least four types).
Here is a paper dealing with Beethoven’s manuscript markings. It deals with Beethoven’s use of staccato - it seems he had 4 different flavors. Interesting reading.
https://www.bu.edu/beethovencenter/files/2017/09/Beethoven-Op.-131-manuscript-markings.pdf