My Samsung A3 has a function called Max Power Saving Mode which I assume is Samsung's version of Ultra Power Saving mode. I find it very helpful sometimes but when this mode alarms dont go off. Is there any way to allow alarms ( set in the clock app) to go off in this mode? I've checked through the settings for this mode and I can't find anything which allows it. I've searched the web and I couldn't fine anything about this though I did find some stuff on UPSM but the settings didn't seem to match.
I discovered the answer literally 1 minute after asking the question so I thought I'd answer it myself in case it's of any advantage to anyone else.
There's a very simple ( but quite odd in my opinion ) solution to this. Simply adding the clock app to the the shortcut screen of Max Power Saving Mode ( by clicking one of the plus signs ) solves the issue completely.
With the shortcut added - the alarm sounds. Without it - silence.