New blogpost from DND Staff on Errata and Sage Advice

Errata and Sage Advice: What’s Next for the New Core Rules? | Dungeons & Dragons

I eagerly await the new SAC clarifying the following RAW issues:

1. How exactly does the Nick Mastery Property interact with the Light Property, Dual Wielder feat, and Extra Attack? How many attacks are permitted per turn? Does the Light Property allow its bonus attack to use a non-Light weapon? Which attacks benefit from the Two-Weapon Fighting Style’s ability modifier?

2. How does the Hide Action interact with Invisible, Stealth checks, Perception checks, and Passive Perception? When should a DM call for checks to detect a hidden creature?

3. Is the True Strike spell a Weapon Attack or Spell Attack? How does it interact with weapon bonuses (e.g., +X weapons) or Arcane Grimoire’s bonuses? Can it be used with the War Caster feat?

4. How do True Polymorph, Polymorph, and Shapechange operate as intended?

   • Duration: How long do they last?

   • Forms: Can they assume specific individuals (e.g., Laeral Silverhand)?

   • Abilities: Do they grant Spellcasting, Legendary Resistance, Legendary Actions, or Lair Actions?

   • Clone Interaction: If affected by Clone, does the clone replicate the original form or the polymorphed form?

Thankfully, had they been more meticulous in the initial release, we wouldn’t have needed to debate these points tirelessly for months.

Thanks Argenix!

Those topics would definitely benefit from some clarifications. I've got a few more things I'd like to see in the new SAC too:

• One Thing at a Time rule and the ability to take a Bonus Action in the middle of other actions (e.g. The Charger Feat combined with the Push Weapon Mastery & Extra Attack)
• Target and Range (you, your weapon or a creature?) of True Strike, and interaction between this spell and Agonizing Blast, Potent Cantrip or Potent Spellcasting (*)
• Emanation when playing on a Grid (e.g. Paladin Aura of Protection or 2024 AOE changes)
• Examples of allowed stacking/timing interactions related to features/spells/Mastery Properties (e.g. Trip Attack + Topple Weapons/ Topple Mastery)
• What's a class spell? (**) Are Eldritch Invocation spells considered Warlock spells for you? Can you use your Pact Magic slots to cast them? (e.g. What exactly is considered a Warlock Spell, especially when multiclassing or Question about 2024 Magic Initiate)
• Are dead creatures still creatures? (e.g. Question about Planar Binding)
• Monsters and Opportunity Attacks (e.g. So monsters can't make Attacks of opportunity), "natural weapons" (***)
• How to interpret intangible things in terms of targeting or spaces (e.g. Conjure Animals 2024)
• Mundane vs. Magical Darkness (e.g. Wording of Heavily Obscured)
• Clarification about Great Weapon Fighting (e.g. Does Great Weapon Fighting Apply to Extra Damage Dice from Spells and Effects?)

(*) True Strike and Agonizing Blast - Rules & Game Mechanics
Does Lessons of the first ones, Agonizing blast, and Magic initiate (Druid) work together to create the best melee weapon? 
2024 Evoker Wizard, Potent Cantrip and Weapon Cantrips 
Understanding Magic Stone and Agonizing Blast (2024 version) 
Agonizing Blast and Booming Blade 
True Strike + Agonizing clarification 
True Strike Question for the Hive Mind 
Agonizing Blast + Radiant Soul 
War Caster + True Strike 
Warlock 2024, taking Agonizing Blast twice at level 2 
True Strike + Potent spellcasting 

(**) Class spell lists - Rules & Game Mechanics
Species spells & Casting level - Rules & Game Mechanics
Fey-Touched Spell Save DC - Rules & Game Mechanics

(***) 2024 wildshape - do you gain multiattack?
Are "natural weapons" still a thing in 2024?
Wild Shape, Polymorph, Unarmed Strikes and Attacks of Opportunity
From comment#37: Natural Weapons Vs Unarmed Strikes

EDIT: fixed links.

As for the errata side of things:

I was somewhat surprised that the development team took a crack at fixing the Hide action but failed to take any action to fix the current functionality of the Invisible condition itself.  It is such a core mechanic that it really does need to be written correctly so that a creature with the Invisible condition is actually invisible.  This should have been very high priority.  Hopefully the next iteration will address this problem.

More topics from the bottom of my heart/mind that I'd like clarified in the SAC:

• Equip or unequip: once per attack, or once per Attack action? (e.g. Draw and Stow Weapon 2024 Clarification, Equip or Unequip a weapon - once per attack or once per Attack [Action]?)
• Interaction between Nick and Eldritch Knight's War Magic (or College of Valor Bard's Extra Attack / Bladesinging's Extra Attack): Questions regarding Shillelagh, War Magic, True Strike and Extra attacks 
• Investment of the Chain Master: when Quick Attack happens? Questions about Investment of the Chain Master 
• Is Cleave part of the Attack action? (e.g. Cleave weapon mastery)
• Counterspell against monsters (e.g. 2024 monster spellcast vs counterspell)
• Interaction between Wild Shape and ASI feats (e.g. Wild Shape and half feats)
• Graze Weapon Mastery and damage increase (e.g. Weapon cantrips and Graze Weapon mastery)

Weapon juggling needs an errata. Specifically the ability to use the light property without duel wielding.

They may think the Invisible condition is more a candidate for SAC than Errata. 

If without magic or special sense you can still see someone under such condition, then i wonder how you can ever be invisibleper se...

Quote from Jurmondur >>

Weapon juggling needs an errata. Specifically the ability to use the light property without duel wielding.

But that's really two separate issues. We can all have our opinion about weapon juggling but as long as you allow any switching of weapons then the issues with the Light property stays. The main issue there is that none of the rules for dual-wielding require you to actually hold two weapons at the same time.