I might have the answer but it requires somebody to test my theory, firstly we are all barking up the wrong tree – If it works for you then just thank me later [email redacted ]
It’s nothing to do with WordPress or the plugins you might have installed but possibly the version of internet explorer we are using:
Example 1: I’m in edit post and in the bottom right hand corner you will see “Set featured Image” right click for options and select to open in another window – you should be able to view “Add media files from your computer”.
Some might consider this as a work around but it works for me – I’m a novice at WordPress but I am a support engineer at RS Components (Nuneaton).