I'm having a silly problem in edit session within ESRI ArcMap 10.4. I'm trying to copy from a polygon feature to a polygon feature and when I'm using copy function the paste function turns instantly grey and can't use it. I've tried deselecting the feature, shut-down and restart of the program but with no effect.

The solution is a total restart of the computer but I don't think this is right. Is there any other solution or someone who has/had the same problem?