Ranged attacks with Icebrand won't add charges to a target if the target is affected by a melee Icebrand debuff with between 2.5 and 1.5 seconds remaining. I don't have a replay for it, but you can test by letting 5+ ranged heroes with Icebrand attack someone with a melee Icebrand debuff already on them and notice only one charge is on the target.
I don't think it would cause problems to just let new ranged attacks keep the melee debuff time (which is going to be near the ranged debuff's duration anyway by the time it impacts) and add a charge.
Fixed internally, thanks for the detailed report!
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