I am exporting the file from Quicken 2017, and the format of the export file is .QXF. The same thing happens if I try to import a QIF file. KMM will not see the file for import unless I change to All Files. If I try to import then I receive the error

I understand the problem about the error, which we probably can't do much about. This binary stuff is not valid OFX data. Doing some more investigation I came across definitions for QFX and QXF. They are complete different things and it looks to me as if QXF is only used to transport data between Quicken for MAC and Quicken for Windows. This would explain the binary (proprietary) stuff that we cannot read. That means, QXF is not supported by KMyMoney. Sorry 'bout that.

BTW, I just tried to import a QIF file. In the file open dialog with the 'Import files' filter selected, I see all *.qif as well as all *.QIF (lower and upper case) files. Doing the same with "*.ofx *.qfx *.ofc|OFX files" when performing an OFX import, I do see both upper and lower case ofx and qfx files. BTW: this is performed with version 5.0.3 and a few patches, none of them related to this problem. I scanned the source history: both cases are available for qif since KMyMoney 5.0.2, for ofx that is available a lot longer (before December 2017)