Do you store your token on Bittrex on 22 June 2020? If so, your token is already automatically swapped into a new one, DAWN. Check the balance on your Bittrex account, if it is empty, then you didn't hold it over that period of time or there might be some issues about the swap.
For full information, take a look at
Bittrex Global supports Dawn token swaps.
Thank you for your answer. This is exactly what I thougth had happened but it was not the case. My Bittrex 1ST balance was the same that back in 2017 and my DAWN balance was zero. I think that some action was required in Bittrex to claim the swap 1ST to DAWN that was performed the 22nd June 2020.
The only way to know for sure is to seek assistance from their support center, it surely will give clarity whether a swap action is required or not. You can also contact them regarding your whole problem.
Also, it would be good if you also ask the token community regarding the Bittrex swap on that specific timeline, see if they also have the same problem or not.