At the moment two things are happening.
1. I set the duration for the individual stills in deck 1, (my visuals). Clips are set to 'Play Next', and it runs as a sequence as expected. Then I switch to deck 2 (other guys visuals) and set the duration for some stills, plays fine... go back to deck 1...duration has rest itself to 5000 on all the stills...
2. Set duration of stills on deck 1. Save or Save As, quit, reopen, duration of stills reset to 5000.
I made a simple one layer, two deck composition and tested this with three still each set to different duration...same problem. Thats the composition I've attached. The still is just a blank png.
2012 Mac Book Pro, OSX 10.10.5
Arena 5.1.1
It'll only take me a minute to set up the durations at the show, so im cool

Thanks!
Craig