Crescendo Hairpins Not Working

It may just be an issue with my settings, but for some reason, the playback of my hairpins are not working when I place them under 2+ tied notes [e.g. four tied whole notes with piano (p) on the first, hairpin between, and forte (f) on the fourth]. If I use no tie between the notes (using the previous example) but keep the dynamics and hairpin, then there's no smooth transition between the notes and the separate dynamics. I know that playback for cresc.'s and decresc.'s works fine in 3.6.2, so what's the deal here? Anyone know how I can fix this? Thank you...