In order to use MTS footage in Premiere Elements smoothly, you should transcode MTS format to Premiere Elements edit-friendly file type.
You will encounter incompatibility issues when import MTS to Premiere Elements. Although the latest Premiere Elements added many new features, it still can’t supportAVCHD MTS. If you have some MTS videos from Sony Handycam, Panasonic, Canon, or JVC cameras, you may want to edit MTS files in Adobe Premiere Element.