Subject basically says it all. As an example:
Mm. 1-4 are correct, measure 6, last C is natural when it should be legato. Same as in the last measure. It’s almost as if starting the slur on the last note of a tie-chain cancels the legato playback technique. Example project attached.
test-slur-start-end - auto.dorico (1.6 MB)
Note: I added Legato to the Default expression map for testing.