The way your logic was built means that the progress bar will work from 0 to 100 while the timer is running. However it will be always 100% if any of the following members is invalid:
Unit → BP Combat Component → Active Timer
This should give you an error on console if either Unit or BP Combat Component are invalid.
If only the timer is invalid, you won’t get an error however you always will get 100% because remaining time will be 0, satisfying the bottom condition and therefore always selecting A in the last Select Float.
You should be able to verify those values at runtime if you add a breakpoint to Set Percent, I hope this helps you! Please let me know if you have any further questions tho.