If you have settings where you use compatibility on your browser on Ebay (I have IE 10 and have to use it), it's a little blue or grey broken rectangle at the right end of your URL bar, you may need to turn it off to be able to get a typing box on Ebay messages, and then turn it back on to make Ebay invoices readable when you are sending invoices, and have a visible cursor if you use the SYI listing form. I also have to vary it to enlarge the auction images.

For the last few weeks I have been having to turn it on and off over various aspects of Ebay, in spite them saying that it should always be turned off.

Kind Regards,  Kevin