I started a new timeline and switched to List Mode, then I decided to switch it back to Timescale, but I couldn't click on the text "Switch to Timescale". After a lot of playing around, I discovered that the click area is a tiny box within the bullet label, but above the text. The List Mode click is the entire text.
Steps to Reproduce
Open a timeline (this might be specific to Firefox, I have no plugins).
Click on Settings.
Go to the Timeline Mode.
If already in Timescale, switch to List Mode.
Mouse over the text of "Switch to Timescale".
Note that the cursor does not change to the click icon, and clicking does nothing.
Move the cursor just above the text, but still within the button, and cursor changes to the click icon, and clicking on it works as expected.