"Hmm...," I thought to myself, "We have a problem here."
I did a little investigating and traced the incorrect lens identification bug back to the latest version of Adobe Camera RAW (v.9.3.1). It seems that ACR is misidentifying images taken with the Sigma 50mm Art. This bug will be especially problematic for those who use automatic lens profile corrections when importing RAW images into both Adobe Photoshop CC and Lightroom CC as the wrong lens profile will be applied.
To counteract the issue, when using the Sigma 50mm Art be sure to manually choose the Sigma 50mm f1.4 DG HSM A014 lens profile from the drop down list if a correction profile is desired. Also note that images saved and converted by Photoshop will display the incorrect lens in the EXIF even if no lens profile correction is applied.
Update: Adobe has let us know that they are aware of the issue and that it will be fixed in the next release of Adobe Camera RAW.