I had this problem too and spent way too long digging into it. The problem is in config/config.js. In the config for the MMM-cryptocurrency module, both “currency” and “significantDigits” SHOULD be arrays. If you’re trying to show more than one crypto, but don’t update “significant digits” then any index after 0 will show as NaN.
Here’s my config as an example:
{
module: "MMM-cryptocurrency",
position: "top_center",
config: {
currency: ['ethereum', 'bitcoin'],
conversion: 'USD',
showUSD: false,
//headers: ['change24h', 'change1h', 'change7d'],
displayType: 'logoWithChanges',
showGraphs: false,
significantDigits: [2,2],
coloredLogos: true,
}
},