1. Is the error condition you found the same as
this page? If yes, maybe the answer in the post can help you, or you can try to contact support team. you can mention them on twitter, I have an answer for my problem within 2x24.
2. If you are using a mobile device, maybe dextools still hasn't activated the feature you selected. The solution, try to follow the warning by making transactions using the metamask extension on your pc browser.
3. To add a new token, please add it manually, just enter the contract address as usual, then you will see the token you have entered. This is not a bug, and indeed for some tokens are not automatically registered on the metamask.