On Epic Battle Fantasy 4 enemies that seem to have their hp bar completely empty still live, but they die after they take one hit. Is this a bug or is it natural?
Yes, It is a bug. However, it is only a minor visual error and it has no effect on gameplay.
If the monster has very few HP remaining, the HP bar may appear empty. As a programmer, I think it is very likely that the number of pixels that are filled in is calculated based on the ratio of current HP / Max HP, and that there was no special handling done if this rounds down to zero.
For example, assume that the HP bar is 300 pixels long (it may actually be shorter or longer; this number is for illustrative purposes only), and that the enemy has 11 HP remaining out of a maximum of 8000.
- (11 / 8000) * 300 = 0.4125
- 0.4125 rounded to the nearest integer is 0
Note that if you have previously scanned this enemy type, you will be able to see their current HP when you hover over the ? icon next to the monster.
I encountered this issue twice yesterday while playing. In the screenshot below, notice that the Red Clay (2nd monster from the top) has an empty life bar but 8 HP remaining.