I know this is probably not a bug but rather EHG are trying to limit the benefits players get from the belt, but because of 2 points that make me think that giving players their own ignites should be affected by the player’s affixes:
1, the description of the belt is like “YOU ignite yourself when…”, the subject is “you” means this stack of ignite’s source should be the player himself, from normal logic it should be affected by the player’s “Ignite Duration Increased” or “Ignite Effect Increased” and “Fire damage increased” etc. . If EHG think this will break the balance, then I suggest changing the item description to emphasize that the source of this ignite is not the player to avoid ambiguity.
2, if the ignites that players apply to themselves through the belt can be affected by the player’s attributes, then players can stack more ignites on themselves by “Ignite Duration Increased” to get more Adaptive Spell Damage. But on the other hand, since these ignites are affected by the player’s %INC , stacking more ignites means taking higher ignite damage, making the player less survivable, which I think would be a great trade-off design.