Seeing that the original Flipdown Timer Card has had no activity in 2 years, I have recreated in a new repository.
I plan to actively maintain and improve across time. Please submit any issues or feature requests that are outstanding and I will take a look in priority order.
To get the ball rolling, the issue with Flipdown Timer Card being frozen when contained in other cards has been fixed.
Also now available for testing is 1.1.0-dev.1 which features a new modern GUI editor. 
Please test if you can and provide any feedback you have.
UPDATE: 1.1.0 released which includes GUI editor and Flidown CSS variables for theming.