Hi,
This is perfectly normal. Only the master is the contact point for the entire pool.
I would advise to go for manual promotion if you consider your host dead. To do it, go on any slave you want to promote (just one) and type xe pool-emergency-transition-to-master. If you use HA, this will be done automatically, but HA can be tricky.
The result will be the same, if the master is down, you'll lose the view in XO about what's going on the pool, until you get a master back.