In your smart contract and ABI, if your event variable name is prefixed by an underscore then Moralis does not seem to capture the event value in the respective server table.
For example, if you emit the below event, only the value for price will be captured and displayed in the Moralis server.
event MarketplaceOrderCreated(
address indexed _maker,
bytes32 indexed _tokenId,
address indexed _paymentToken,
uint256 price
);
I noticed this when testing how to capture events, and I was using a Ganache development blockchain. Once I removed the underscores, then the event data was properly captured by Moralis.