On March 10th 2020 Energi started a new blockchain called "Gen3" as an upgrade of their old blockchain. Though Coinomi attempted to reach an agreement and support the new blockchain, unfortunately that was not possible so the new chain will not be supported at launch. Don't worry, your coins are perfectly safe. As long as you have your recovery phrase you can always access your coins.
While the Energi team has their own instructions for swapping to the new chain, following their procedure is not recommended! You should never enter your recovery phrase on an online device or an online web form. This can put the security of all coins (not only NRG) at risk. Please follow the instructions below if you have NRG in your Coinomi wallet.
Step 1: install a Gen3 NRG wallet
Download and install an NRG wallet compatible with their Gen3 blockchain, and note down your Gen3 address
Step 2: get your list of funded addresses
Open your Coinomi NRG wallet and select "... / Show unspent outputs" from the top right corner. This will list all addresses where the app knows you have funds. You can note down each individual address once. Noting only the first 5 characters of each address should be enough to find them on the step 3 below.
If you no longer see any balance and no unspent outputs, you will have to find out your funded addresses by trial and error with steps 3 and 4, or use a Gen2 block explorer (for example https://nrg.tokenview.com/) and follow your transactions on the block explorer starting with your first receive address until you find your funded addresses.
Step 3: get the private keys of your funded addresses
Follow the instructions here to get the private key of each address you noted down on the previous step. The page on these instructions works completely offline. It doesn't receive or send any data, unlike the NRG swap tool. The key export tool can and should be used on an offline device for greater security.
Step 4: perform the migration on Energi's website
Open https://nexus.energi.network/coin-migration and select "Single Gen2 key". On the text box below it, enter one private key obtained on the previous step. After entering it, the page will show its NRG balance. Click "continue". After that enter the Gen3 address you obtained on step1 above. Read the rest of the information of the page to check everything is correct, and start the migration. If you have multiple funded addresses with Gen2 NRG, repeat this last step for each one.