Background selection window slide control has stopped functioning.

My Windows PC version background selection slide control is not responsive from the Video settings in the online window of the app. I am able to choose from selections I have already uploaded as long as I don't need to scroll down to choose one, and I am able to add new ones. It has been working correctly until recently. Now the scroll bar is frozen, and will not allow me to scroll down to other backgrounds I have uploaded. I have updated the app to the latest version, but the problem remains.

However, it functions normally from the settings/background & effects in the desktop window. That changes the online background as it should.