We're not having any problems importing files downloaded from Chase here. Perhaps your recent download doesn’t actually contain any valid data or became corrupted somehow. First off, you might try redownloading from your bank, taking care to set a Date Range that you’re sure contains one or more valid transactions. If that doesn’t help, would you consider sending a file over to us in an email addressed to
support@splasm.com, so we can have a look at it? (Unfortunately, the provided link doesn't allow us to download anything because it seems to require validation using your Chase.com user-account credentials.)
Do be aware that OFX files often include account numbers right at the top (labeled “<ACCTID>"), in the header, but you could replace yours with Xs—feel free to open the file in TextEdit to do that, or type over whatever else you see that you don’t want us to see.