[Q] horizontal apps sometimes have blacked it portions topic

I have a T-Mobile HTC m8, not rooted, and with the latest lollipop update. For the past two days I've been getting a weird issue. A horizontal app had part of its screen area blacked out. I can press home and the home screen is fine. Other apps are fine, but if I go back to the troubled app, it's has the blacked out area. This happened to monkey city, and Google maps. Any advice is appreciated:)

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