When I enter a tempo marking, only the text appears and the dotted continuation line does not show. How can I make the dotted line appear together with the tempo marking?
If you mean something like a ritardando tempo marking, in the lower panel there are options in “Gradual Style”.
::: Bill
It only appears as “Immediate tempo.”
How do I change it in this case?
There’s no way to change the type of a tempo mark from immediate to gradual (or vice versa).
If you’re using the tempo popover, you’ll notice that tempo words are recognized by Dorico as immediate, gradual, or relative. The same is true in the tempo panel. If you want to force something to be, for example, a gradual tempo, you can enter something which is definitely a gradual tempo, like rit, and then use the Properties panel to change the Text and/or abbreviation to something else. (And turn on the extension line.)
Thanks.