USO not shortable

Anybody know why Alpaca has USO marked shortable=false? Is it a temporary thing because of the reverse stock split?

“id”: “adf623fb-f91a-4e45-aa66-6fb8f3677b23”,
“class”: “us_equity”,
“exchange”: “ARCA”,
“symbol”: “USO”,
“name”: “”,
“status”: “active”,
“tradable”: true,
“marginable”: false,
“shortable”: false,
“easy_to_borrow”: false

USO is currently hard to borrow.

Yes, I see that from the shortable and easy_to_borrow flags. I was wondering if Alpaca provides more color as to why.