My macbook pro retina (early 2015) stays on a grey screen after waking up from sleep mode

Hello,

My macbook pro retina (early 2015) is not waking up properly after sleep mode. When I open it to wake it up after sleep mode, the screen is grey, but I hear sounds from emails coming in etc... So it's a screen-problem in my opinion. The only way to make it work again, is tot do a hard shut down by holding the on/off button a few seconds and than start it up. After starting up, the macbook works normally.So the problem only occurs after sleep mode.

Has anyone else had this issue? How can I fix it? Is it a hardware problem?

Isabelle