If I had assets with BlockFi which declared bankruptcy and locked my assets for a period of time before I was able to recover them, am I able to claim any sort of loss based on the opportunity cost of the time it was locked.
For example, if I purchased the crypto for $1,000.00 but then it became locked during the bankruptcy and inaccessible, and the price went up to $2,000.00 during this period, but by the time I was able to control my assets again it was $1,000.00, which I now control and still own, is there any tax claim or write off in this case based on the opportunity cost based on the banktruptcy?
Sorry to be the bearer of bad news, but there is no tax write off for the potential lost gains while your funds were inaccessible during a crypto exchange's bankruptcy proceeding. You didn't actually realize a gain or loss to have a taxable event when you were unable to access your funds.
This is true whether it's a situation such as you proposed where you could have realized a gain on your crypto, but for the bankruptcy keeping your currencies frozen, or if you would have liquidated your funds and taken cash out to reinvest in another asset.