Fedora provide mp3 import with libmad. But audacity seems not compiled with libmad so can't open mp3 files.
This bug appears to have been reported against 'rawhide' during the Fedora 26 development cycle. Changing version to '26'.
audacity-2.1.3-2.fc26 has been pushed to the Fedora 26 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2017-c6511f96f9
audacity-2.1.3-2.fc24 has been pushed to the Fedora 24 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2017-ec5e8e0240
audacity-2.1.3-2.fc25 has been pushed to the Fedora 25 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2017-a20103b1c8
audacity-2.1.3-2.fc26 has been pushed to the Fedora 26 stable repository. If problems still persist, please make note of it in this bug report.
audacity-2.1.3-2.fc25 has been pushed to the Fedora 25 stable repository. If problems still persist, please make note of it in this bug report.