After updating to Lightroom CC 1.4 (June 2018 release), the Medium Contrast and Strong Contrast tone curve options and the saved curves are missing in the Tone Curve panel.
Lightroom CC 1.4
Windows and macOS
To streamline the interfaces and make the tone curve process consistent, the following changes have been introduced in Lightroom CC 1.4 (June 2018 release):
Going forward, the tone curves should be saved as a preset so that they can sync across the Lightroom ecosystem of apps.
Use the link below to download a zip file containing the previously provided Medium Contrast and Strong Contrast tone curve options as a conventional preset. The zipped folder contains the following XMP preset files:
After unzipping the downloaded folder, you can import these XMP presets into Lightroom.
If you've used Photoshop's tone curve to create saved curves or have saved curves in the past via Lightroom Classic or an earlier version of Lightroom, follow the instructions below to restore your existing tone curves in Lightroom: