Back again.
I checked the link and the ‘known’ issue from Adobe was one that featured in Encore 1.0 but was fixed with the first bug fix.
The issue related to the first frame playing and the rest freezing. This problem plays the still of any duration for exactly 25 frames (PAL 1-second), the first frame of the video remains frozen for a further 4-seconds and then the video plays correctly afterwards. The total freeze time of 5-seconds is the actual duration of the still as indicated by the timeline in PP1.5 and oddly in Encore 1.5 itself!
Mmm, puzzled. Will sleep on this for a further night in the hope that something comes to light while I snooze!
Thanks again.