The tokens are most likely swapped. It happened with me that tokens were locked and they automatically sent me new tokens with a new symbol and kept the old tokens locked. You should keep following such projects on telegram or discord to be informed about the swap else you'll lose those tokens. Some projects require you to do KYC to unlock the tokens.
Sometimes, they swap tokens from one to other chains (for example, eth to eos). Anyway, the best way would be to ask the project staff, it's funny to me how many people don't care to be up to date with project happenings.