They never said completely or 100% in CNBC or other press, so WSB are alleging that they only closed some low percentage of their positions, which makes sense mathematically. Closing out ALL the shorts at $300-ish/stock (closing time) would be disastrous to any fund, with the shorts predicated on last months' Gamestop prices of around a single digit.

Disclaimer: I do not have a position on Gamestop or any other US stocks.