I enter 08:10 in the stop field, save the program 5, see that the value is still 08:10, exit the programs page, re-enter into program page, re-open program 5 and find 00:10 in stop field back again !!
To see whether this is a UI problem, you can try to use the classic web interface (instead of the app) and see if you can reproduce the issue. To do so, open a browser and type in:
where x.x.x.x is your OpenSprinkler’s IP address. This should show you the classic web UI similar to shown here:
Try to change program settings using this web UI and see if you still get the same issue.