Cannot select and copy certain text within apps

Until recently, any text displayed within an app could be selected and copied. Recently, certain text cannot be selected with press and hold or double tap. For example, I am using the chat feature in a banking app. I sent a message to support and, after sending, tried to copy the text of my message but the phone will not allow me to copy any text. What settings do I need to change to ensure that all displayed text can be selected and copied?