Generally, you can't take the capital loss until you realize it (make it real, by selling, or having it declared worthless, etc.). As long as there is still an open recovery process, the amount of your loss is only speculative. When the recovery process is closed, and you recover whatever you can (whether some percentage or zero) then you would report the capital loss.
Can you find someone to buy your rights in this investment today, maybe for $1? Then your loss is realized and you could deduct it on your 2024 return (it is too late for 2023). Then the person who bought the investment from you would get whatever money does get paid out in settlement. Otherwise, you need to wait for the process to conclude.
