Hello! First of all, make sure the bar you created correctly inherits from GradientBar_Base. If you correctly duplicated one of the existing bars, this should be the case. Then when adding the gradient to your layout make sure you set the bar ID (case sensitive too!)
See the attachment below. If all these are correctly setup, could you include a few screenshots that show the widget settings etc? Because the ones you include seem fine. (Also make sure that the cast to TopDownCharacter works)
Finally, you should be calling “update bar” whenever your health/mana changes. In the showcase map this is done in ‘mycharacter’ blueprint (attachment below)