I don't know why it stopped working, but OFX files have become associated with a different program (Microsoft Office Accounting Professional 2009) and I cannot seem to change it.
The Unassociate program, mentioned in another thread, does not run under W10.
If I right click on an OFX file, and try to select another app on this computer, browsing to "C:\Program Files (x86)\Microsoft Money Plus\MNYCoreFiles\mnyimprt.exe", I get a popup indicating I cannot do this:
The file can be imported into Money from the Money File menu, so the file itself is OK.
Help would be appreciated.
Ron