Keyboard Doesn't always appear/pops up and down.

Hiya,

So I've recently just come back to Swiftkey after originally using it as one of the early backers from Kickstarter.  Thankfully some of the bugs like the very aggressive emoji auto correct have been fixed.

However on my iPhone 6+ I'm getting quite frustrated with it already.  The keyboard isn't always present on my apps - Whatsapp specifically. As in the default iOS keyboard shows instead.   Plus if I do tap the switch keyboard button, Swiftkey will pop up and down a few times.  It may or may not stay up and sometimes it just goes back to the default.

If I'm going to use Swift... I want to use it all the time and I don't want it to be a faff.  Can anyone help me with this?

Cheers,

~ Ed