Bizarre issue that only started today, and I haven't installed any new addons. This also occurs with no other addons enabled.
When inputting text into the addon settings, such as changing an item's name, it repeatedly selects all text without any input. In other words, placing the cursor anywhere in the field, and leaving it alone, results in the text suddenly at random selecting itself. This gets in the way when actually trying to input text, as it will overwrite itself as you are typing.