Ties in Ms 2.1

It's been a while since I have posted.
D/L'd Ms 2.1 and so far I am happy with it, all previous files work as expected.

That said, I have found an anomaly that I can't fathom.

In the attached piece that I am working on.
The tied notes in bar 7 play back as individual notes, (on my PC anyway.)
The tied notes in bar 3/4 play back as expected.

I am probably overlooking something obvious in something I have done but can't find it.

Thanks Alex.