Summary: This article explains why a user might not be receiving staking rewards in Cere even if they have more than the minimum bonded amount. It details the dynamic nature of the minimum nomination amount, the "bags-list" feature, and provides a guide to repositioning an account using Cere Explorer.
Although 250 CERE is needed to be able to nominate, not all accounts with more than 250 CERE staked will participate in the election and get staking rewards. The minimum nomination amount needed to participate in the election (support a validator) and earn rewards is now dynamic and can be found on the Targets page of Cere Explorer:
Recently we saw the implementation of what is called the "bags-list." With the bags-list, all accounts that have declared the intention to nominate are put into "bags" based on their stake. The bags are ordered based on the stake, and the top 22,500 accounts are selected to participate in the election algorithm. As a result, the minimum bond needed to earn rewards is a dynamic minimum equal to the stake of the 22,500th account instead of a fixed amount of CERE.
If you are staking over the minimum amount and still aren't receiving rewards, your address may need to be repositioned in its bag. This happens because bags are sorted based on stake, but the accounts in each bag are not. So, in the last bag, only the first X accounts will participate in the election. But since the accounts aren't ordered based on stake, accounts with higher than the minimum amount may be excluded because they found themselves in a lower position in the bag.
Accounts can put themselves in front of other accounts with a lower stake but a higher position in the same bag using the voterList.putInFrontOf* extrinsic. This requires knowing which account to put your account in front of, but the Cere Explorer does everything for you with a button click.
This process only puts you in front of an account with a lower stake. Therefore, the process doesn't guarantee that you will start getting rewards: it's possible that your account may be put in front of an account that itself isn't included in the set. However, if you have staked more than the dynamic minimum, you should start receiving rewards after the next era.
Sometimes accounts can find themselves in the wrong bag, e.g., as a result of slashing or auto-compounding a lot of rewards. Pressing the "Rebag" button on the Bags page (if you see one) and signing puts all of these accounts into the correct bags. It may not include your account; anyone can rebag any misplaced account.
This will realign your position within the bag and hopefully allow you to begin receiving rewards again!
If you're not getting staking rewards, there could be other reasons too. For a comprehensive list, see "Why am I not Getting Staking Rewards?"