I have noticed this as well. I run Windows 10 and use both Internet Explorer and Microsoft Edge - mainly to decide which is better. When running CCleaner, Internet Explorer is cleaned as it did before Windows 10 was installed but the process then stops at a request that Microsoft Edge needs closing. Until this is ticked either Yes or No , the process will not proceed.
I don't know how to refer this to Piriform, there seems to be no way to send them a query.