Dispel Grenade Durability Bug

When you use both mats and a durability infusion, something happens to where it visibly says it has a higher durability, but, in actuality, does not get the benefit of the higher durability.
If you add materials with durability and use the durability infusion, it will show that it has durability damage to it that cannot be repaired. In this screenshot I've got two dispel grenades side by side, one with both a mat that has durability and the t3 durability infusion, and the other that has no durability. The one with durability shows it as having 55/85 durability and the 30 missing durability cannot be repaired (yes, I have enough essence).
The one without the mats with durability or a durability infusion is at 15/15.

Edited because I missed where it showed the increased durability stat originally.