The .oma file extension is for a Sony music format file; these files are in Sony's ATRAC3 format. The .oma format is a copy-protected format, and when confronted with one of these protected files, Switch will appear to convert about a minute of the file before it gives up (this is a property of the file itself and not our software).
We only support those proprietary formats where the format creator has published some sort of plugin or means to be able to convert out of the format. In the case of .oma files, Sony has not done this (to our knowledge), therefore our hands are tied. The format will only let you convert 1 minute of the file as part of its protection mechanism.
