Has anyone tested this yet my mate wanna go hit titans.
Well he went out and come back. All is cool. Still in the war.
I don’t want to take responsibility but … as long as you have the warning timer and come back well before it runs out, you should be okay 
I am throttling back in a dead alliance. One of today’s POV challenges is to “attack a titan 3 times”. Problem is we get 1* titans. I kill those in 2 hits and I killed my last titan before today’s POV daily challenges came out. So, next titan spawns in the middle of the night. I cannot complete the “attack a titan 3 times” without leaving my alliance. So, I did my first 3 war hits and left to hit a titan 3 times. But when I came back, I discover that I am now an ex-member in spectator mode for rest of war! I don’t remember this being a problem before. In any case, the war exclusions are confusing and people will keep getting caught out.
Welcome back to the forum Lim.
In the two years I’ve been playing, if you leave your alliance during war, any unused flags can not be used when / if you return. Similarly, any war rewards you may have received, are now forfeit. This has always been the case AFAIK. You would have had the warning prompt before you left your alliance?! That is new 
.
FWIW you don’t need to complete every daily mission to finish PoV to level 48/50.
Having enjoyed chilling out on dead alliances and fighting one star titans, I found it takes some patience to figure out how to manage them. I would often hold my hits until I saw the PoV requirement. Often I would need to use baby teams to get my three hits done.
It’s just a matter of trial and error.
Thanks for the responses. Yes, I do know that we do not have to complete every POV, but last POV, I somehow miscounted and could not finish the last POV stage, Granted it was only an avatar, but it was the first time I did not complete. Chilling out too much! So, I thought I should be a bit more on the ball this time. But I received no warning when I left my alliance, so was unpleasantly surprised.
Thanks! Certainly quite a different experience!