iPhone 6 using iOS 8.4 keyboard locks while using iMessage or text feature. Usually noticed when the letter "T" are will not respond to touch until after a long wait. Usually 30 seconds to a full minute.
While composing an iMessage or text, the keyboard intermittently "Locks", especially if trying to type the letter "t". Sometimes, the suggested word in the banner above the composition area will have the word I want and that will respond. But, if I try to continue typing after attempting a "t", non of the other letter areas will respond unless I wait patiently. Sometimes not too patiently!
iPhone 6, iOS 8.4, Intermittently issue