This item is new for 2020.
The underlying LLC is a single-member LLC with no shares issued/authorized. Is 0 an acceptable number? What if I leave it blank?
Somewhere I read that for an LLC, use units.
If there are no units, make up a number - 100 or 1,000.
I don't think you'll be able to efile with zero or blank but you can try.
I had that thought too, but I'd be concerned if the client actually incorporated the LLC at some point and issues shares.
Would it be okay to change the number of shares on subsequent K-1s?