The recast works just fine if you have 80+ ward.
The issue is that when it recasts in that cast doesn’t count as spell cast towards Spellblade nodes such as “Spellbound Weapon” or “Blade Weaver”.
This issue seems to appear with other recast skills as well - such as Enchant Weapon with the recast node - even though the enchant weapon isn’t a skill - if you take the elemental node in it it works as one - but when it becomes auto recast - it loses that synergy - keeps using elemental nova, but it isn’t counted as spell cast from the passive nodes and item interactions.
PS. There is another issue with recasting Fire Shield skill - for example I have 5 points in “Capacitor” passive as Spellblade and 5 points in “Spellbound Weapon” - If I cast lighting melee skill (Mana Strike) it adds accurately 25% melee dmg - every time I recast Fire Shield after - the Fire shield will add those 25%, working as lighting melee skill. If I cast a spell - like Teleport - it adds 45% melee dmg - every time I recast Fire Shield after - the Fire Shield will add those 45%, mimicing Teleport Skill… If I cast Lightning Blast - it will add 25+45 (total 70% as skill and lightning one) - every time I recast Fire Shield after - it will add again 70% - so it appears it mimics the type of the last skill casted.
Tested it with The Invoker’s set as well - if I cast Elemental Nova - it adds 80% to all 3 types of dmg… every time I cast Fire Shield after… it mimics it and adds 80% to all elemental dmg as well