You can see that the slur from the eighth not D to the dotted quarter C is just fine. But then when I try to create a tie from the dotted quarter C to the whole note C, I get this:
I’m assuming you want the slur to end on the dotted quarter C. To get this to happen, select the slur and then open the properties panel. In the properties panel, you’ll see options for both the start and end positions of the slur. You can set these options on a project wide basis in engraving options.
Yes, of course they are different. But that’s not at issue.
The question is whether you prefer the slur to end at the start or the end of the tied notes. I think most modern engraving style guides suggest slurring to the end (and from the beginning) of ties. But feel free to choose a different default.